This doesn't make it clear how people will run the end products.
Is it targeting the web? If not then it's not going to be useful for the same things as Flash was.
It says:
> HTML5/Canvas export — Export to self-contained HTML5 with JavaScript Canvas 2D playback.
Call me crazy, but I think the folks at newgrounds will figure out what to do with this new flash.
Apart from the HTML5 export mentioned by another commenter, there exists Ruffle[1], a Rust + WASM reimplementation of Flash that can play swf files. It's used a lot on archive.org or on some websites like https://homestarrunner.com.
[1] https://ruffle.rs/