I wish I could share this sentiment because Flutter really does look great, but I don't think it will succeed as long as it's based on Dart and not JavaScript.
The big G dropped the ball on Dart 1.0, which was rescued by the AdWords team.
Right now Flutter/Dart looks like an ongoing political war between ChromeOS, Android and Fuchsia.
By the way, Fuchsia is getting Android suport and a new language agnostic UI composition engine, Scenic, so lets see for how long Flutter stays as the Fuchsia official UI toolkit.
But isn't the point of a truly cross platform framework just that? So what if fuschia has a different native toolkit. Maybe they are trying to launch a platform specific api that's more bare metal.
I mean Isn't the whole point of flutter is that you take the same app and run it anywhere?