I have a small little theory I concocted this morning:
As you all know, we just had our first new, unique third party in the form of Simon Belmont. I personally believe that Simon will not be only unique third party present in Ultimate's roster, based on this quote about Sakurai here:
https://sourcegaming.info/2016/02/23/nintendo-dream-interview-with-sakurai-part-2/
"—Final Fantasy VII
(FFVII
below) has never been released on a Nintendo console, so how did Cloud end up appearing in Smash
?
Sakurai: Final Fantasy (
FF below) is one of the few uniquely Japanese game series revered by players around the world. I think fans across the globe have hoped a character from one of those series would appear in
Smash, so it was only a matter of time. At the same time, there are only so many big-name titles we can work with at this point—mainly because we’ve covered most of those bases. Aside from the major globally-recognized franchises already featured in
Smash, there really aren’t that many left."
What this strongly suggests to me is that there will be, at least, 1 or 2 more third party newcomers from Japanese franchises that are globally popular after Castlevania, going by what Sakurai said about not having "that many left." Which franchises they could is a bit of a mystery, but if I were to guess them, I believe it would be a character from Tekken and Resident Evil, followed by Kingdom Hearts and Professor Layton if there are more third parties he has planned for Ultimate's roster.