Ultra Necrozma is what I wanted Kyurem to be and what I hope Arceurs will become if Sinnoh gets a remake, the god of aall pokemon should not be so weak that mega evolved Rayquaza and mega evolved Mewtwo outclass it and Kyurem desperately needs a form where both dragons are incorporated into it, I can't believe the sequel games didn't have it, the fact that the manga is constantly talking about it makes me think maybe the author has a design in mind for it or he knows something we don't.
Not only is N currently about to fight Ghestis but he's also got White and she has the light stone with Reshirem in it, there's no way that both dragons aren't going to be fused when both of them are right there.