i'm curious how the OOTB JSX support will be used

i wonder if it's conceivable to ever write typescript in a REPL

There are both ocaml and haskell repls, so it can be done with languages whose type systems are the focus. Not sure if there's anything specific about typescript that would make it hard, though.

unrelated but i couldnt help but notice - is that screencap (https://techcrunch.com/wp-content/uploads/2019/05/Screen-Sho...) using the Windows Sets feature?

Nope! The new Terminal supports tabs, all by itself :)

an asian white nationalist - now that is something to behold