Logically the Enclave can't totally be destroyed I'm sure there are remnants all over the Wasteland probably in the the North West, Mid West, and South East because there is not a whole lot of people that would rival the Enclave in those areas other than the Brotherhood of Steel in the Mid West but if we go by the canon of the series a lot of the Mid West chapter had moved to the East Coast which is where most of the Brotherhood members in the Citadel came from Chicago. The Enclave certainly is still around and if they would ever get a foothold again and re organized they could be a force to be reckoned with. That was just my opinion on the matter and it would be really cool and I think possible for the Enclave to make a return in any future Fallout titles.
Sincerely,
Prizrak