I kind of feel like this is when everybody converted codebases to CoffeeScript and are now stuck with having to undo that...
Yes, I get strong typing has merits - but so does writing the native language.
Naturally. But the merits of strong typing far outweigh those of writing the native language, for me at least. If you have a project of any reasonable size, TypeScript is such a huge productivity boost it's incredible.
I was very sceptical (having indeed been burnt by trying CoffeeScript before) but the comparison doesn't really work with TypeScript. If it died tomorrow and we all decided to go without it, we'd just transpile to JS and be done with it - CS -> JS looks very, very different, but TS -> JS is the exact same code, just with types stripped out.
But even if all of that does go away, types outweigh writing without types imo - but you can always take the output of TSC and stop using it going forward, its not obfuscated.
Big difference is that ES 6 has indeed replicated most solutions of CoffeeScript. However so far I can tell ES won't be ever(?) statically typed and therefore it won't ever(?) solve same problem space as TS.
That said, you would expect more of a middle ground like Python where Typescript type annotations become syntactically valid in ECMAScript but with no clear semantics at runtime, and Typescript would still be needed to compile/verify type assertions.
There's also the case that transpilers will likely remain test beds for both future features for the language and supporting complicated backwards compatible scenarios.