All-New, All-Different Avengers is going to follow the "All-New, All-Different" X-Men formula to a T. It's going to be one of the originals, with the rest being newbies. My guess would the original will be Iron Man. And new cast members will be distinctly more diverse.
Roster Prediction:
Iron Man as the leader
Union Jack
Nightcrawler (making both the X-Men and Avengers roster!)
Miss America Chavez
White Fox
Radiance (Ryoko Sabuki)
Female Thor
And one new superhero
Why would they have a series set after Secret Wars start during Secret Wars? Wouldn't that spoil the outcome?
You guys are forgeting Hope Van Dyne. I bet she will be in the team.