Well, it's kind of an issue, because it's a similar argument for platforms like Xamarin. A third party still has to keep up with mainline. That means another layer of support, maintenance, dependency… which is not always an issue… but practically speaking is one of the things you eliminate at scale and / or in the rigors of production.
Fair enough; it still seems pretty promising, especially because my experience developing native Android apps did not make me feel confident in doing very advanced UIs with native Android - it just feels complicated, and the compatibility layer stuff seems like no fun. (I had trouble linking the jars in for reasons I was not able to fully understand. I've worked with Java stuff before, but the Android toolchain still has me confused.)
I hope that Flutter, with its massive backing, manages to stay up to date with mainline without putting too much burden on app developers. We'll see I suppose.
