I thought the end was surprising too--is Watanuki actually seeing the future, or is it just his expectations? I'm not clear on that, and I really can't think of with whom Doumeki would be living at the temple, he's clearly not the marrying type, at least for now. I also think that Doumeki/Kohane seems off; I really do think that's just a departmental rumor.

But I don't know who else would be living at the temple besides Doumeki, either; they tend to run in the family.