But just because it says 'New challenger/fighter' doesn't necessarily mean that the character has to be entirely new. I view the term 'new' in the sense of each character coming
into the game is new to smash 4. You could also look at it in the sense of the other veterans that have returned. On the website, it would say 'NEW!' next to each character on their banners as they were updated.
If Sakurai includes the Mewtwo from the Genesect movie this time, then technically she'd be a newcomer.
All we can do is continue to hope anyhow.