I agree! WASM is very interesting. Blazor is an exciting example of an application of Web Assembly - it's starting out as .net in the browser, but you can imagine a lightweight wasm version of the .net runtime could be used in a lot of places as a sandboxed runtime. The main .net runtime is not really meant to run unprivileged. It would be more like the UWP concept that MS made to sandbox apps for the windows App Store, but applicable to all OSes.

One thing I haven't heard much about is the packaging of wasm runtimes. For example, instead of including all of the .net runtime as scripts that need to be downloaded, we could have canonical releases of major libraries pre-installed in our browsers, and could even have the browser have pre-warmed runtimes ready to execute, in theory. So if we wanted to have a really fast startup time for .net, my browser could transparently cache a runtime. Basically like CDN references to JS files, but for entire language runtimes.

This would obviate the need for browsers to natively support language runtimes. It's conceptually a way to get back to something like Flash or SilverLight but with a super simple fallback that doesn't require any plugin to be installed.