Look up "Dreams" on the PS4. This is absolutely today's version of that.
There’s a difference in distribution freedom though. HyperCard and Flash were conceived as production tools. You could interface with other tools and APIs. For the finished work, you could put it in a box and sell 6 million copies (like Myst), or host a game on your own server (like everything in the Flash golden era).
The Dreams runtime is a console game — a prerequisite investment, and limited audience compared to desktop / web platforms. Hopefully they’ll offer some kind of player-only licensing program for creators eventually?
I suspect that a truly open platform/distribution would never realistically exist alongside something of this quality. It's a nice idea but it just wouldn't happen.
Something simple enough to be good and free is probably also not going to catch the attention of this generation of budding creatives.
A distributable runtime, to a market of 100,000,000+ PS4 (plus PS5's), royalties to creators as publishers, would be an intermediate step.
Bundled with PS5 for early gen content.