That's kind of the goal.

Recent efforts to strip browsers down to their core functionality, and provide a world where the current web is effectively userland code:

* web components

* service workers

* Houdini

Imagine a future where browsers just implement these low level concepts, and HTML is defined as an (open source/community) library that all vendors bundle as part of their browser.

And then, also consider how much overlap there is here with traditional operating systems. Your next device OS could be just another layer on top.