Websites have spent the last 20 years removing user customizable functionality (think RSS feeds and making API private). While the tech may be possible, I don't see this being a reality without a major reversal in app development philosophies.

Companies want to control what you see so they can control their revenue. Why would they want to expose their data and utility to UIs where they have limited ability to monetize?

Technically possible now, I suppose. If you're Google and have the analytics, you could make a standard site layout and munge every site into that format based on usage data. Neat idea.

Firefox Reader mode does a decent job of this.