Most tech innovation works off Metcalf's Law, meaning that very little will change until... all at once everything changes. That was the way that Intel took Sun's market share in servers and it will be the way that ARM eventually takes Intel's market share (very slowly at first, and then all at once).
So by all means, don't hold your breath - it could be several years. But when you start to feel the impact it's already over. Better to find a more stable company than wait for the swift end.