They're Dead. Navarro, Oil Rig, and Raven Rock are done for. They are probably in Chicago, but lets remember that they are pitted with the Brotherhood over it (I think).
*waits for Mr. Enclave and Lt. Andronicus to respond*
Don't want to keep you waiting.
I completely agree with you though (except for the use of the word "dead" as that implies they're
all dead). As it has been hinted at in the games, they're is likely still a few outposts in Chicago, with both an original garrison force and surivors form the east coast (not very many though). If they have to go up against a powerful MWBOS, they'll be annilated most likely, unless they are able to stay hidden. However in Fallout 3 we also get word (although we don't know how reliable it is) that the MWBOS have fallen on "hard times" which could give the Enclave remnants a chance to survive.
Or possibly, if the MWBOS are under General Barnaky, we could see a Remnant/MWBOS alliance. Now that would be awesome.