Semi-Immortal God Queens probably don't die as easily as you'd expect. Particularly if we're going to end this book with shuffling off to not-Britain (I think Africa is next on the list?). It's just...not something I expect to happen.
I mean, it could, just I don't see it as likely.
Information that points to the Beacon Lucrezias being from after her many warps, though it also is solely based on information that Agatha herself had learned (meaning it could just be Agatha-Lucrezia pushing buttons as a complete bluff, without actually knowing anything relevant).