I think it'd be sort of a cop out to have Ankh revived through Haruto's magic. Just like, "Hey, now we can bring back Miura Ryosuke whenever we want without having to provide an explanation".
Watanabe being back I can understand, but, yeah. I'd rather save Ankh's revival for something bigger. IF they are going to do something with it that is. They may just leave Eiji fighting by himself since Megamax was probably his last movie where he was a significant character, and we don't necessarily need Ankh to bring back OOO anymore.