Most of the world are nowhere near the sorry state that the US is in, so they can't really shut it down. Might have to find a new server to host the project, but that is pretty much it.
NSA (or someone else) could try to include a back door, but let's say that people review the changes, so it becomes known. Fork, bad mouth truecrypt, recommend NoBackstabNewTrueCrypt instead.
I really think that there are enough FOSS zealots here for this to happen, so I am not particularly worried.