Well, maybe not infinite. But it's the best explanation I could come up with for Brutaka's "us". But if anyone has a better theory, do tell. =)
And personally, I found the Takanuva thing a bit far-fetched.
On the Ancient matter, true Greg can kill whoever he wants, but I think he's become addicted to it. We've known Ancient, for... a few chapters in serials/books? And he's already gone.
However, it was a smart move of Greg. Now we'll never find out The Shadowed One's real name.
EDIT: Nightmare, that's not that bad an idea... It does seem to fit.