KamilTrebunia
Google would have to replace the whole stack (from HTTP to DOM to Dart to IDEs) to make it really compelling, but I'm pretty sure they will give it a shot.
Fortunately there is a competition:
Nobody will dedicate himself to Chrome Web Store and Google Web technologies and miss out on future Facebook WebApp Store (or whatever Project Spartan turns out to be) or future Apple AppStore (I believe in Apple's intelligence and visionary and that they will realize potential of Open Web and Clouds in time).
Android also is in trouble so unless Google will win the mobile market big time it will get more fragmented and thus forcing everybody to jump into Open Web and not Google Web.
And then there's Mozilla - let's hope they can pull off some good piece technology with their B2G and Firefox Mobile!
At least that's what I want to believe...