I think this was the original vision of XML: eXtensible markup language. With globally unique names XML was meant to produce a whole world of languages that could've been developed independently and mixed together in the same manner as Unix command-line tools. E.g. XSLT is a language for a XSLT processor; XSL-FO is a language for XSL-FO processor and so on. In this schema XHTML would've been a language for the browser that would co-exist with the rest of the ecosystem.

> I think both applications and media would benefit > from a split of html into seperate language for > defining app-like sites, and traditional content pages.

This! I would go a step further, even. The "web-applifier" community should just leave the classic web and do their own:

* protocol (I am sure, HTTP is not ideal for serving apps) * GUI description language (document markup language for UI design, really?) * runtime (let them have WebAssembly and whatever they need) * each app then could have their own window, making it look like a traditional app

so... like Java swing or Adobe Air? I don't know all the reasons technologies those failed to deliver, but I do think that being able to deploy from the same platform that users use to discover the app (that is, the browser) as well as almost effortless instant updates has a lot to be said for it.