I think I'd prefer a sequel rather than a prequel. We already know how it ends up, so unless, as others have said, a prequel could come up actors on par with Garber, Rifkin, Olin (frankly, the whole cast with few exceptions), it wouldn't be anywhere near as satisfying as the original. A sequel at least moves forward, with new, unknown stories to be told. It doesn't even have to be with Syd & Vaughn's kids - maybe it's Mitchell (Marshall & Carrie's kid) or one of Dixon's kids or Will's kid (assuming he has at least one kid with the lady he married in Wisconsin). It's been so many years that someone like Rachel could be pretty high up in the CIA hierarchy.