> Incidentally, it would make the browser vendors themselves fairly obsolete, which is probably why it hasn't happened yet.

Mostly, but not entirely true. It's been a while seen we've seen a new browser come out, but the time is ripe to begin work on one, and release it in a few years. Just fork webkit to maintain backwards compatibility. I see browsers just becoming a sandbox virtual machine with a key ring, with minimal functionality.

Apple has the strongest incentives to build what I am mentioning. Not sure if they will.