Weyoun and/or the Female Changeling might have had a reason to say that the Dominion has been around for 10000+ years. We already know that the Cardassians are an ancient culture (at least several hundred years), not to mention prideful. Perhaps the Dominion anticipated that the Cardassians would be more impressed by an empire that has existed longer than they have, and thus more succeptible to join. Or maybe that was meant for the Breen. Thus, to continue having them as a major partner of the Dominion, the story would have to continue.

Similarly, perhaps the Dominion wanted to put some sort of propaganda inside the Federation's head. Thus, this explains Weyoun-4's line from "To the Death". For all we know, maybe the Dominion has only been around for five-hundred years or so. 2000 years is enough to impress me--10000 might be enough for other races.

Well, it's just a theory. Or a bad-continuity-writer's explanation postmortem. Whatever

------------------
THE DOOMSDAY MACHINE