It is a very interesting question to ponder. If you see the web as a logical progression from email->newsgroups->gopher->www then clearly what was missing were the missing links. Once we had those everything else grew exponentially. But the web was clearly not intended to become an application platform. At the same time now that it has become an application platform we are facing a difficult choice: stick to incremental improvements and all kinds of hacks to shoehorn application interfaces into a document model (an awkward fit at best) or, alternatively to see where that progression could go next. How to preserve the 'link' feature and the advantages of the web while addressing the gap between native apps and web apps, improved user privacy and security, less reliance on verticals.

That's a very tough nut to crack.