That's not a positive, though.
Depending on how it pans out, it's either not useful enough. Who the hell doesn't use namespaces or enums. Or - as
These constructs are not in the scope of this proposal, but could be added by separate TC39 proposals.
implies - a door opener to outsource TypeScripts problem unto other peoples and not to investing into improving WebAssembly. That's just MS being lazy and making their problems other peoples problems.
I feel like this would be the ideal scenario: things working right out of the box without needing a compile step or additional tooling.
It's just annotations. No proposed semantics of a type system which your browser could check on its own.