Super Smash Bros developer Masahiro Sakurai has stated via a Japanese Developer’s Conference that the next title in the series will include brand new characters to choose from. The next Smash Bros game is currently under development for Wii U and 3DS and both versions will connect together in a certain way.
“It’s fun making new skills for new characters.”-Masahiro Sakurai
Just to clear things up. The previously Masahiro Sakurai said the number of characters in Super Smash Bros Brawl was perfect. Nothing was ever said about there not being any new characters however some people misread what Masahiro Sakurai said and took it as not adding any new characters.
I suspect most if not all of the 3rd party characters will be replaced with newer ones. So far the most likely new character from what I have read about the game will be Lloyd from Tales of Symphonia. I would like Krystal from StarFox Adventures to appear in this game. Not enough female characters and I like StarFox. A character creator would be perfect though.