Avengers 4: Every Character Confirmed So Far
6. Rocket Raccoon
Confirmed By: Sean Gunn
Again, Rocket's involvement was pretty much confirmed by Saldana to the BBC, but Sean Gunn also confirmed as much in an interview with Fanfest around Guardians Vol 2's release.
He revealed that he's filming on Avengers' projects until "the end of the year at least", which means he was on Avengers 4 for at least several of those months.
It would have been foolish for Marvel to kill off Rocket - particularly when the idea of a Rocket and Groot spin-off movie would be so lucrative down the line. And with James Gunn charged with expanding the cosmic side of the MCU, there's no way that film won't be considered.