In my opinion.. - Major Spoilers.

Rating: 10/10 (4 May 2018)

The movie is perfect so just go watch it. But there's a few things about the ending that give away the next film. I immediately thought, once he snapped his fingers, that of course along with half of the world, some avengers are eating dirt.
Once they started dying I actually gasped which was embarrassing but once Black Panther, Peter Quill, and Spiderman all died I thought oh well who cares cause obviously they are coming back; they wouldn't kill these new and important characters that easily. This is the only thing that ruined it for me because now the next film is so obvious.
The one thing Doctor Strange said to Tony about this being the only way, makes me think they have to die and Thanos has to win so that he can let his guard down in the next film and they can get the stones and revive everyone.
The one thing I'm confused about, isn't the Spiderman Homecoming set in 2020? He's not an avenger in 2020 and he's still as young in this one. They clearly messed that up. He also would go back on now having the Nano suit. It doesn't make sense. Homecoming completely contradicts the entire thing but I'm sure it was a mistake.
And they already confirmed Guardians of the Galaxy 3 and yeah you could assume it's a prequel and that's probably what they want you to think but come on, they're definitely brining them back. They killed off a ton of characters because they have too much and the next movie will be better with less powers and characters for however specific they choreograph the fight. Honestly if they had every single one together they would win so fast.
Plus if Captain Marvel is as strong as they're saying she is, they'll need less powers to give her a spotlight and really kick ass at the last second.
Anyways, my bet for the next one, thanos will probably kill some avengers (for good). They will probably get the stone, resurrect whoever with probably some kind of consequence, destroy the stone, and when you think it's all happily ever after, someone will die, and they'll be screwed because the stone will already be destroyed. And if I'm correct, I better get a damn cookie.