I'm expecting the cast to be around 20-30 characters, but because I love getting overly excited about these kinds of things, I have just complied the characters I'd like to see in the game. This is probably going to make me disappointed by the size of the final cast, but here's my ultimate cast of about 70 (!) characters, which will never happen but I can dream of it.
And then an actual, although some of these might be less probable (highly doubting any from 2,4 or 5) , cast of 30 characters that I'd be happy to have.