Carmack is going to be my barometer of sorts.
If he stays, it means for now at least Facebook is not interfering. If he goes, Oculus is good as dead.
This is the first thing I thought of. Carmack won't let his original vision of Oculus go. If he leaves, Oculus might as well be dumped into a pile of shit and never retrieved.
On the other side, piles and piles of cash could make Carmack's original vision leave stealthily and cleanly.