Really, no takers for Caelum? As a neighbor, I'm kind of torn, as I could certainly take advantage of a Caelum AI

Then again, other neighbors of Caelum are probably in an even better position
I would consider Caelum a major power at this point, and well worth subbing in for, and conversely, also quite unbalancing for a game a lot of people have put a lot of time in, if they were to go AI.