Sandboxing of the browser is much more important than that. Apple and Google built their own sandboxes for mobile, I think personally we should take the best open sandbox env and expand. Wasm is a great start, does multiple languages and easy to port to new platforms. Human friendly higher level capability wrappers / ACL could be built around it.
Apple and Google are excellent at moderating against malware, and that is a serious barrier to entry. But a bunch of publishers fed up with paying Apple and Google might be motivated enough to invest in an equivalent community infrastructure.
