Got to agree with everyone x-3 has to have less Wolverine,he's been rammed down our throats in the first two movies.And frankly i'm sick of him,give some of the other characters more screen time,all that Wolverine in x-2 is the reason Cyclops,Rogue etc got a crappy amount of screen time.After all it is called the X-MEN,and not Wolverine and co.
X-Men 3 Plot
As seen at the end of X-men 3, i think that surely the storyline will revolve around the Phoenix. And it would be logical too, since Cyclops and Jean Grey haven´t got a major role on the two previous movies.
In that order of ideas, maybe the new entering characters could be the Inner Circle (some or all of them) or the Shi'ar (sorry if it´s badly written). The additions to the X-men side i think could be the beast, Angel and Gambit