[pax_americana]

Google libraries are a different story compared to their software products. AngularDart is hardly used outside of Google that it's practically dead and no longer maintained for use externally. However it's alive and well inside Google and still have internal releases within the company. Since Flutter is heavily used outside as well as inside, Google will have to consider the man-hours of rewriting everything Flutter has touched in order to decide dropping it, which means never basically. So even if Flutter is dropped by the community using it, it would still be maintained by Google for their internal use.