I built a little Android/iOS app in Flutter and it was a real delight. I didn't especially like Dart at first, but it was easy enough to pick up and then got out of the way more or less. I'd love to be able to easily run an app like that on the web. I know Dart's original vision was to replace JS but it seems they backed off that a bit. But it sounds like it's back on the menu!
I don't know if this changes anything exactly, in terms of what Flutter can do right now. I think web/desktop have always sort of been there. But what's new for me is this perspective that they intend to support other devices beyond mobile. I wasn't really sure about that before, since it seemed mostly tailored to just iOS/Android when I was working with it.