Re: Changing the roster for Avengers 2?
Well they should keep in Iron Man and Hulk because let's face it, those two are the money makers for the GA. Then Cap and Thor were a big part of things especially for the connectedness of the MCU so it'd be wise to keep them on board as well.
However Black Widow and Hawkeye either need to step up their games or fade to background characters. It won't be hard for ScarJo to play eye candy even if she isn't physically on the team. And I know Jeremy Renner wants a bigger role but I doubt most people will really miss him if he isn't front and center in the action for Avengers 2.
So what I'm trying to say is keep the big 4 but make Widow and Hawkeye just SHIELD agents who work in the background with Fury and Hill.
It's probably safe to say Falcon will be on the the team due to his involvement in Cap 2 so we have him. Ant Man is a maybe and Wasp is a weaker maybe. Then a good possibility for Guardians making an appearance as well so I think that'll flesh out the team plenty.
If they choose to go on to make Avengers 3, there'll be more wiggle room for "rotation", a bigger roster and things like that.