What if Despicable Me 4 had changes: Antonio Perez from Despicable Me 2 will make his returning appearance where Margo made amends with her love interest as being Margo's boyfriend and larger role, before get adopted by Gru as Gru's second son at the end of the movie. Also, he was recasted by Anthony Gonzalez for the fourth film.
But he would become as a sub-dued character for this fourth movie when he try to show both Gru and Margo that he has changed after he realizing the changes that chould happen to him, like such a real love between Margo and Antonio as fully recovery, before he gets adopted by Gru at the end of the movie.
Donny, the minion who still stuck his head with jelly jar would reappears at this movie.
The title card "THE END" would been in the style of Despicable Me 3 title card as a throwback, and it would be only seen at the end of the movie after the song "Everybody Wants to Rule the World", in which this film is being a grand finale.
Gru would become just like Loser Kermit Luke from Star Wars films.
The previous villains from Despicable Me and Minions movies would team up with Maxime Le Mal to get their revenges on Gru and his family, despite they will stay the same aged for this movie (and they didn't aged throughout the movie), but they will turn into good guys at the end of the movie as redemption arcs in the AVL's prison after they feel betrayed and guilty, and they would fight against Maxime Le Mal with the help of Mega Minions, the girls, and Hyperman, just like Teenage Mutant Ninja Turtles: Mutant Mayhem in the final battle and climax scene, although they're going back to the AVL prison (except for Mega Minions, the girls, and Hyperman), and the film ends when they seeing Gru, Hyperman and Maxime sing "Everybody Wants to Rule the World" after Gru and Maxime had reunite as best friends.
The previous villains wouldn't get greyed hairs, nor some minor wrinkles throughout the movie.
The Vicious 6 would stay as humans; despite turning into rats at the end of The Rise of Gru.
The previous villains will finally respect Gru at the end of the movie, just like Kung Fu Panda 4 when they seeing Gru, Maxime, and Hyperman singing karaoke and a cover of "Everybody Wants to Rule the World" as album cover for the original song.
And Maxime would had his different line "We coming for our revenge, Gru!".
Scarlet and Herb and Vicious 6 will recognize Gru in this movie.
Unlike the first third previous films, this film would be a musical for the final film of the franchise to compare to the Disney musical films.
Gru is officially canon immortal in this fourth film to be kinda like a super-hero immortal.
The girls would stay the same aged for this final movie.
The girls would have a larger roles in the final battle scene where Margo have an idea to Lucy and they will enter Super-Serum to transform the girls into the super-heroes to save Gru and his baby from Maxime Le Mal, and after Maxime was defeating, Gru would be so proud to the girls that they saved his life (just like he rescue the girls from Vector in the first film)
Then, when Gru and his family returning to their original home, Dr. Nefario will reverses the girls and Gru Jr.'s transformations.
This fourth movie would be the last film and the grand finale of the franchise.
As a result, Despicable Me 4 will serves as the last film of the franchise, and this movie would be a series finale to feel like an end-game of the Despicable Me franchise.
Illumination will make a title card of Despicable Me 4 in the classic Despicable Me 2 title card style (but with orange color) to be a throwback.
Unlike its previous films, the 2013 Universal logo wouldn't appear at the beginning, nor "UNIVERSAL PICTURES PRESENTS" text. It was replaced with the text says "ILLUMINATION presents" in the first scene.
Gru will remain as good guy forever throughout the movie.
Heitor Pereira would be using the score from the original three films including its spin-offs to be a series finale for the franchise.
Ralph the Minion will breaking out the vending machine earlier to help the Girls to save Gru and his baby at the climax of the movie.
The final battle scene would be more epic and more heroic between Gru, the girls (who enters AVL's Super-Serum to turn them into super-heroes), and Mega Minions vs. Maxime Le Mal and the previous villains from previous films.
The song "Everybody Wants to Rule the World" would being the perfect ending of the franchise to end Gru's story arc to being the last movie of the franchise after says "Nothing ever lasts forever".
Poppy will sing her verse "I can't stand this indecision, married with a lack of vision, everybody wants to rule the world".
Mega Minions are fully accepted by the townpeople after they capture Maxime Le Mal at the climax when the camerman has shooting them for every country with the help of reporter woman to explain Mega Minions' good intention and the crowd are reconciling with the Mega Minions, and the Mega Minions would become the true and really super-heroes team of all time.
Also, Mega Dave is used SR-6 (as using more often throughout the movie) to shrunk Valentina (except for dog) as being arrested and give to the police to send her into AVL prison, and the police guy would thank to Mega Dave "Thanks, <PRESIDIO_ANONYMIZED_PERSON>. This tiny woman is going back to the jail for a long time."
The Mega Minions are celebrated by townpeople as the real super-heroes, since they are finally good deed.
The Mega Minions are become the true, coolest, and fully and greatest super-heroes after defeating Maxime Le Mal.
After the final battle scene, Silas would appear to congrate Gru, and declare him the officially greatest super-hero in the world, and Silas Ramsbottom asked Poppy to become a Gru's super-hero sidekick one day, and she accept him and she then goes to the AVL's school of heroes to learn how to become a super-hero sidekick alongside Honey Badge, before the crowd chant "Gru!" "Mega Minions!". He also form Gru and Mega Minions into officially super-heroes team.
By the end of the movie, Poppy along with Honey Badger was transferred to Anti Villain League's super-hero school to learn how to become a sidekick to the super-heroes for the future.
Gru would stayed as a hero and good guy throughout the movie, and being an both super-hero and AVL agents, when the people cheers him "Gru!", "Gru!", "Gru!", with the police says to Gru "Thank you, Gru. You done it again. Let's take Maxime and the other villains back to the jail. Take him away, boys."
In the end credits sequences and credits rolls of the last movie of the franchise:
"Despicable Me Theme" by Pharrell Williams would plays as a third song in credits rolls, while "My Life" by Robin Thicke would be plays as a second song to be throwback.
In the first opening scene, the song was replaced with the song "Shut Up and Drive" by Rihanna, while the new song "Double Life" by Pharrell Williams is plays instead at the first half of the credits.
"Harder, Better, Faster, Stronger" by Daft Punk's song plays with a remix, when the five Minions enter the Super Serum to transform into Mega Minions scene.
Mega Minions will actually doing a good deed as really a super-heroes, for example:
Mega Gus would actually save the man cleaner, instead of let him cleaning the window.
Mega Jerry would never let a sonic burps after he eating a time bomb.
Mega Minions would finally doing their fully good deeds as coolest super-heroes.
Mega Tim would used his stretch to stop a thief instead, while Mega Dave would stop an out-of-control train with his strong power, similar to Mr. Incredible in Pixar's The Incredibles scene when he stop the train, and it wouldn't not throw them to hit a building. Due to its switch places for Tim and Dave.
Mega Minions' first mission would be succesfully rather than failed, and the crowd will cheer to Mega Minions.
After the five minions transform in Super-Serum to Mega Minions, they will used their powers to saved the world like the other super-heroes, with Mega Dave saying his first English line "It's hero time!".
The Mega Minions will remain their heroic forever as the truly super-heroes.
Unlike the other minions in which they had minionese voices, the Mega Minions will finally be able to speak fully English like the humans who speaks, although they still sounds like Minionese by Pierre Coffin.
Mega Minions will speak more English talk more often and sound in this movie, kinda like the first Despicable Me in the trailer where one of the minions trying to talk the text "DESPICABLE ME".
The crowd will cheers Mega Minions after they doing their first test successful rather than failure, then, Mega Minions will become officially Anti-Villain League's new secret-weapon.
The women will give the red flowers to Mega Mel after he rescue the cat from the tree.
Mega Mel wouldn't get accidents by laser the cat's fur on their back and cut the owner's hair, since he's got under control.
By the end of the movie after defeat Maxime, the Mega Minions are celebrated by the townspeople joining by polices and AVL.
Stuart, Jr. as a chick from The Rise of Gru, will reappears in this fourth film as a adult rooster along with Otto from the same movie.
The fourth film also had a new character "Hyperman" (He is a original super-hero, nice and kind guy, speaks Minion, has powers just like Superman, and has the same personality as Metro Man from Megamind, and he is a new member of AVL). And he was voiced by Michael B. Jordan. By the end of the film, Hyperman will become friends with Gru and Maxime Le Mal (after redeem himself to sing the cover of "Everybody Wants to Rule the World").
As a result, Hyperman would stay as a original super-hero through the entire movie.
In this film, Gru and Hyperman is closet super-hero friends.
Bob and Otto from both spin-off movies "Minions" and "The Rise of Gru" would become canon in the current timeline of Despicable Me.
Bob would be appear in more screens other than the ending. Example: Bob (with his Tim teddy bear) is eating cereal along with the left side of Kevin and Stuart where they are eating, and in end credits, Bob and Kevin are running from Stuart when he continues to pelt Kevin and Bob with the gun pegs.
Otto would be appear in two scenes, where he is eating donut (he also seen the left side of Bob, Stuart, and Kevin), and at the end of the film, where he is playing with pet rock (during the sing "Everybody Wants to Rule the World").