Conversation so far:
When did the lineup change?
March 2015.
what were the changes?
Hoppus and Barker decided to continue on without DeLonge.
who did they replace him with?
and enlisted Alkaline Trio vocalist/guitarist Matt Skiba to "fill in" for three shows.
what happened after those 3 shows?
Hoppus and Skiba had been wanting to work together musically for several years.
did it work well for them?
After legal battles with DeLonge were worked out, Skiba joined Blink-182 as an official member and began preparations for new music.
what where the legal battles for?
CANNOTANSWER.
Did Skiba stay with the band?
Skiba joined Blink-182 as an official member and began preparations for new music.

Question: What album did they release?
Self-contained rewrite: What album did Blink-182 release?