After a lot of thinking and looking at the wiki, the East Coast Enclave was the remnants of the West Coast who relocated. The Enclave also does have a form of goverment; and we have never even seen, let alone killed, anyone but a couple of presidents and military commanders through the two games the Enclave appear. Our kill-counts can be impressive, in the hundreds, but this is the remnant of the entirity of the whole US Goverment - which knew what was comings and had plenty of time to prepare. There could very well be thousands of them, if not hundreds of thousands.
There are still many places that the Enclave could dwell. They may very well be doing a BoS and be waiting in massive underground complexes. They could be in any of the areas in the US we haven't seen in a Fallout game. In New Vegas, if they introduce it, I wouldn't be surpised to see they are keeping quiet in Area 51. Their vertibirds gave them amazing range of transport for the wasteland.
No, I think we haven't seen the last of them on thinking about it. And, if we have, I think Bethesda may be making a mistake.
The NCR are all well and good but i have to admit I don't find them enthralling; nor did I find the Legion that interesting, so aside from the fate of the Mojave i'm not hoping to hear more about them. There arn't a whole lot of large factions that are intersting in New Vegas (imo, of course). Playing the Enclave Comander mod in NV is a joy. Watching six men with Gatling Lasers take out the ENTIRE Legion Fortress by themselves was amazing. As was calling in a missile strike on Caesars tent. The Enclave are the 'awesome badguys' with all the superior tech. It'd be a crime if they are gone. So, at this point i'm just deciding til proven otherwise that they hold other areas of the wasteland. =D
Your thoughts?