Why? What are we gaining by cramming everything into the browser? We already have OS'es, networking stacks, and technologies for remoting out the UI of server based apps, as well as techniques for delivering code to where the data lives. Why not just use a tool that was designed for the task in question, instead of building some unholy golem-like chimera of parts and bits and pieces cribbed from here and there...
Seriously, a modern web-browser /web-app combo seems like something better suited for a Lovecraft story (I'm thinking "Herbert West: Reanimator" in particular) than real life. :-(
Actually, yes, at least sometimes. Web based email clients are useful on occasion, but that has nothing to do with the point I'm trying to make, which is that we could do something better than either "traditional" desktop apps, or golem-like chimera apps crammed into a web-browser.
Why not use the browser for navigating hypermedia and then let the browser handoff to a different app to do things that require richer interaction? It doesn't have to be a pre-installed traditional desktop app... there's the aforementioned JNLP, and who-knows-what-as-yet-uninvented approach. I'd love to see more people spending time on that "as yet uninvented" thing that trying to turn a browser into a crappy X server, and goofing around with nasty, brutal hacks like AJAX.
I think you are overselling X server, I don't know if you've ever tried to use X over a network but it's pretty awful. The web is not a crappy X server. It's a much much much superior approach to the X server- in that it allows code to run in the gui without the latency of sending every single mouse click and key press over the network, and every single low level drawing command and uncompressed pixel put back.
I think what you want has already been tried with Java applets. Java applets had 10 years to establish themselves as the one true way to make professional web apps and replace the OS. It was a monumental failure of epic proportions, and javascript+html won that battle a thousand times over. Now you want to try it again because .. why? Because you think it's a technically better approach. It's just history disagrees with you.
The web can work over a modem and crummy mobile phone connections. X would be hopelessly unusable under such conditions so it's a complete mystery to me why you are claiming that the web is a "poor man's" X-server. You'd have to be half mad to think that. The web could be 10 times more shitty than it is and would still beat X for quality and responsiveness. So really... HUH!? WHAT?
Seriously, a modern web-browser /web-app combo seems like something better suited for a Lovecraft story (I'm thinking "Herbert West: Reanimator" in particular) than real life. :-(