You can't currently "compile JS to Wasm", you can compile a JS engine (likely written in C++) to Wasm and run JS inside that (almost certainly at lower speed). So instead of "no more V8", it's closer to "ship V8 as part of the website, instead of part of the browser". Exposing DOM APIs to Wasm is a completely different question, though even those would actually have to be new APIs with a new API design that works for Wasm, since the existing DOM APIs are effectively defined in terms of JS objects being passed around.
I didn't know this, thanks for explaining. If DOM APIs could be reworked for wasm support, and JS can work with those APIs, that would suffice. It won't get sites off normal JS any time soon. As far as speed, is it an optimization problem? I'd think just running bytecode is faster than interpreting a script. It doesn't need to be backwards compatible with existing JS code, it just needs to be possible to write front end code in JS for WASM. Migrating to the new approach could be similar to migrating away from Flash, ActiveX and Applets, but at a much larger scale.
10-20 years from now, is it really ok to be stuck with JS and CSS? The complexity is compounding, ever newer webapi's get encoded as JS APIs, and the dependency mess will only increase. Browsers are about as complex in some ways as an operating system. If we think about the world in terms of decades, what is the plan? This is a very serious issue, because of how much the world depends on browser tech, and effectively, Google is the arbiter and overseer of that technology. I don't think this will work out well, unless there is some timely foresight in the architecture.