It probably would if we didn't have people there.
Besides that, I seem to rember reading that we'd signed some kind of agreement not long ago requiring us to come to Muscharraf's aid if Pakistan were attached. I could be wrong about that, but I'm thinking it was part of the deal for him to let us in there.
I think you're right. Very interesting situation. I suppose our agreement with Pakistan could change if we determined that Muscharraf was not in control. Pakistani supported terrorism might be all the evidence needed to change that agreement.
But we need both Pakistan and India working with us, so I don't think we'd dump either unless there was absolutly no other choice.