It's understandable. The rooster is gigantic already, and the high amount of 3rd party entries makes all of them coming back more and more difficult. I don't think that Smash will go anywhere below 50 fighters anymore, however, so many will still come back either way
I know the roster is massive these days, but there are still many more characters out there with the potential to be great Smash Bros. fighters.
The only other option they have is to be included in a Smash Bros. clone (It worked for Rayman at least).
Some days I just blow up.