If this ships, it'll fulfill the "editor" piece of the flash equation. We're still missing the "runtime" though (if we want that old flash feeling). We'll probably need to strongarm Google into supporting it in Chrome, but that's not impossible (especially with AI-enabled coding eroding Google's moat).
He's promising both HTML5 and SWF export, I don't think we really need a new "runtime". Ruffle is pretty close to full AVM2 support.