Valve's main bargaining chip would be not allowing their games to run on Oculus. The recent push back on Oculus exclusives and Valve willing to float cash to developers means they are well aware of their situation.
So I really don't see how Valve is too concerned about this. If facebook locks down the rift so that it can only play rift games, more fool them. Many people just wont buy a rift.
Even if the Vive fails in the long run, there will likely be many other HMD's that will work with steamVR. Valve can still make a nice profit from all the VR games sold on steam.
In the end VR is going to be on a tiny fraction of computers for a long time. There will be waves of improvements and a few hype cycles (3D TV anyone?)
PS: Sure this time it's different, and next time it will also be different, and the time after that...
maybe I misunderstand but Adroid is targeted by many app shops.