Flipping a membership site

Has anyone here ever flipped a membership site with current paying members?

All my current members are subscribed and paying by paypal to my account. If I want to flip this site what is the best way to resubscribe them to the new owner's account?

Why wouldn't they be transported with the database?

Good question, I would be interested to know the answer as well, as I'm thinking of buying a membership-type site.