In a way, a she-hulk movie poses more problems than hulk does. Most of the time hulk only shows on screen when it's time to "smash" things. This is easier to portray with CGI than say Jen spending most of the movie "hulked out" and interacting in a more day to day manner.
Aren't you forgetting Avatar
or Rise of the Planet of the Apes
? We've definitely reached the point where performance capture can create a convincing, sympathetic, emotionally expressive lead character, provided a film has the necessary budget and expertise. And after the success of The Avengers
, there's no doubt that Marvel would have the budget.