Honestly if that ever happened I'd like to see it unfold--since there's no actual game and it's never been stated to be confirmed as a game, it's little more than fanfiction with some artistic assets (fanart and fandubs, respectively) made for it.
I'd love to see that one try and happen, since it would basically have to turn into a case of "well you're gonna have to go after every other piece of Castlevania fanart, fandub, fanmusic, and fanfiction out there for this to fly."
Holding the IP and copyright doesn't make one invincible to legal discourse, after all.