I've proposed an idea several times that I think might resolve this situation, but it's never received any real uptake and I can see some serious issues with the approach. Instead of building a "inner system" ( https://en.wikipedia.org/wiki/Inner-platform_effect ) where the browser uses HTML, CSS, and Javascript to create interactive applications, or attempting to make a sandboxed and highly limited execution environ…
Webpages being rendered framebuffers would be terrible for consistency and accessibility. All the logic for layout computation, responsive design, font rendering, and literally thousands of other things browser have developed over the decades would go out the window.
But on the topic of multi-architecture, that’s really what web assembly is. I’d be surprised if it didn’t continue too become more important, it looks like it’s escaping the browser and into backend apps and server code too.