Won't happen. You'll never find a better character than Fox Fox is the man!
I know for a fact as long as they dont change up Fox too much, he will still be one of the top dogs if not the best. Captain Falcon for melee in my opinion is good for n00bs, but if your an advanced player hes not so good. But you never know, they might a lot of new players and some may very be better than Fox, but i dont know. Lol i do wonder what its going to be like to be Snake...