Barring the character development thrown into the trash, I don't think Kaine has the kind of know-how to pull it off. Peter certainly doesn't, and Kaine's supposed to be as smart as he is, maybe less since he doesn't put his wits to work much. If it's something purely mystical, still doesn't make much sense, cause the Other doesn't really seem that altruistic (or even sufficiently powerful) to be resurrecting non-totems left and right.
What I'm trying to say is, I hope it's not Kaine... He does look too young to be Warren now, though, but he could've used his own tech on himself for all we know.