Yeh, a future where the default way to use an app is via HTML5 makes me sad because it's just so *-backwards.
I appreciated it when people found ways to create user-interfaces in HTML and JS because it was attractive for certain use-cases - no extra software to install on client; updates are made once on the server; works on a variety of platforms. Originally what they could do was limited, and gradually browsers have been improved to make more and more possible without questioning: if the original goal was creating a technology to make application user-interfaces work cross-platform, and remotely, would you end up where we are now with HTML5?
I think the answer is emphatically: no. You'd probably end up with something more like Silverlight. But because Silverlight isn't a 'standards based effort' and also because it's not very ambitious (MS sees it as competition for Flash rather than as a replacement for the web), most industry effort is behind HTML5.
I wonder if the reason HTML5 and other gimmicky frameworks are becoming so popular for application frontends is because of the lack of any native, sane, modern, and first-party UI framework in Windows.