Is the xbone going to fall off a cliff?

[Darwinianevolution]

That will depend of Microsoft's interests. Most multiplats will come to the XBone, specially if they catter to a western audience, but the moment the PS4's userbase surpasses the XBone's three to one, Microsoft will need to push the system a lot heavier than now. Maybe they won't find it worth it, or maybe they will. As long as it's profitable, doesn't loose money and keeps a healthy brand name, they will push the console.