Truth be told, only reason I wouldn't want them to replace characters is because I know the prettiest girl in the game would
probably be on the chopping block T_T. Rightfully so, and I agree with everything said in your post, but she's the most fun to me outside of many characters playing similar roles with different twists. Her dirtbag XTREME father wishes he could be 1/10th as fun as her. Wolverine is the epitome of boo-urns for me >:| Would also suck to lose someone like Taskmaster, who's not necessarily a "core" Marvel character but is as good an addition as Dormammu.
At least the rest of my team would be fine... an Avenger and the company mascot would have nothing to worry about. Hawkeye is a fringe choice but he's pretty unique and I think they'd let him stay.
I don't think there is another game without replacing some characters, and I really love the cast of this one.
Capcom side can do whatever they want, those guys are le suxx.