> It would be nice to get to do that again

The answer to this is both "never gonna happen" and "you already can."

You already can ship a React app in pure JS and even import modules via ESM in the browser from CDN. Performance will suck but you can.

You'll never be able to actually have a complex web app that you can just drag into the browser. As the base API expands, so do the ambitions.

Heck we've had PHP 4 years after HTML just to fill in some blanks, people will always want more than static code.