Honestly KOS-MOS is way too unlikely for this leak to be real, I don't see it happening. Even if Namco did ask for KOS-MOS (not impossible but already unlikely), Nintendo would probably refuse as they would surely prefer a Tales rep, and it would be weird to custome both Tekken and Tales to pick Xenosaga instead.
Anyways, Nintendo seems to always go for characters, not for publishers and I don't think there is any precedent of characters getting in with publishers asking for specific franchises instead of others. All these theories about publishers slots seem really pointless to me, there is very little reason for Nintendo or Sakurai to represent specifically new publishers in Smash or avoid representing twice the same publisher, people don't care about that. It's not even displayed in the game, each series has a logo, but there is nothing about publishers.
If anything, it's easier to work several times with the same publishers, so it's not surprising if we get already represented publishers. It would make sense that FP2 characters are just follow ups to base-game or FP1 negociations, maybe FP2 is just leftovers of what they had planned but couldn't add earlier, at least it seems to be the case for Steve and Sephiroth. Interestingly, for now in FP2 we've only got represented publishers in FP1 so maybe that will continue. Similarly, I believe we could get more spirit promotions or assist promotions, since they are already in the game, they might be easier to work with, so it's a bonus for Shadow/Eggman, Rayman, Isaac, etc, who are already good candidates. With this reasoning, a Capcom character could also happen because they got Ken in base game. But it's not very good for Activision or Koei Tecmo, since they got nothing in the game (except Fatal Frame spirit for Koei Tecmo ?).
So in the end, right now I would bet against Hayabusa and Crash.
On the other hand, Namco is probably a special case since they are developing the game. The odd thing about Namco is that Sakurai hinted at them recently when he said they often not remember that they have a character in the game. It could go both ways though, it could mean they won't get more, or it could be a hint at a future character.
I don't know where Indies would fit in this pattern. At least for Touhou, it's probably as easy to negotiate as first party, and very easy to work with since there is only ZUN to communicate with. Maybe Touhou is the 6th slot that's been added later on top of 5 leftovers from FP1 and basegame, it would fit with the timing of the ZUN interview.
So my current guess at the rest of FP2 would be :
- Yuri Lowell (with the return of Lloyd costume), or Lloyd with Yuri as costume
- Monster Hunter Monster (with the return of hunter costumes), if Pokemon can add monsters, why not MH.
- Reimu