Regarding iv), I disagree that one should not expect this to happen. There's a stage 1 ES proposal for allowing TS-like syntax in the browser: https://github.com/tc39/proposal-type-annotations So there's good reason to believe this may actually happen in the next couple of years.
Everyone (including the authors of the Type Annotations proposal) seem to be on the same page that static typing - "including TypeScript in a browser" - is not desirable and will not happen.
For the avoidance of doubt, the Type Annotations proposal is not actually static typing, but just a 'fancy comments' for the JS interpreter to completely ignore.
