Ok, so everyone knows Makuta's the universe now. I bet what's gonna happen, is Orkham's gonna teleport under the coliseum with some powers he got from Jerbraz. He takes a disk launcher, and a reconstitution disk. He shoots Makuta's essence with it, causing it to reconstitute into a Makuta fish!

But! You're saying somebody needs to inhabit the universe?

Well, Orkham walks towards the Makuta fish with a knife, for a tasty meal. The Makuta fish leaps up, takes the knife, and cuts his head off with it, and then Orkham's spirit floats into Mata Nui's brain.

Isn't it so obvious? They totally set all that up.