that will /should probably make their way into JS.
Not really, IMHO. The main advantage of TS is that it will help you catch errors without having to run a particular piece of code - i.e. you won't have to move to the third page of some multi-page form to discover a particular bug. In other words, it helps you catch bugs before your code even reaches your browser, so it doesn't bring you much to have them in the browser.
(There isa proposal to allow running TS in the browser, which would be nice, but you'd still run a type checker separately to actually catch the bugs.)