there's no chance that webrtc is a more important innovation than XMLHTTPRequest... the web would be just a bunch of hyperlinked text and images without XHR...
Yeah it would have been an interesting world if Java hadn't sucked so bad (and MS hadn't tried to kill it) and the web had remained a hypertext document platform and all the deep interactivity ended up in applets and Java Web Start apps. Both pros and cons to that.
Java, Flash, Silverlight, lets not pretend that Java was the only attempt. Sad part is that flash and java plugins got killed over security exploits while the always growing API surface of current JavaScript implementations still gets consistently owned in Pwn2Own style competitions.
Last I heard you still had to call out into JavaScript, manipulating the same old DOM to get anything done.
Maybe someone could set up a library that implements Swing on top of a HTML Canvas? Just waiting for all the classes to download would help with that nostalgic feeling.