Yup, SES would address this. But SES also needs to bring with it a paradigm shift for JS:

a) Folks would have to load each bit of code they want separate permissions for in a separate compartment. This won't be easy. b) Runtimes will need to provide an immutable global realm, which is not something that is the case right now.

As I said in a different commeent, I think a lot of this can already be addressed by ShadowRealms. Deno will likely allow users to specify per ShadowRealm permissions, which is probably as granular as most people will want to get.