On a Dissidia Final Fantasy livestream hosted by Square Enix, a Kingdom Hearts version of Sephiroth was revealed for Dissidia Final Fantasy as an outfit. It appears to be based off of his Kingdom Hearts variant, instead of his Kingdom Hearts II variant, just like how it was in Dissidia 012 Final Fantasy. You can check out a few screenshots of the livestream below:

You can view the livestream in its entirety here:

(Sephiroth can be seen at around