They should de-emphasize Dart and refocus Flutter development around Kotlin and make that a first class citizen and untangle flutter from Dart. Kotlin already is the language of choice for Android development has a very similar style to Dart (as in Dart provides few if any advantages that I'm aware off). Google already supports Kotlin in Android studio and adoption over the last few years has been enormous. Providing continuity for Android developers is hugely important.

There's a Kotlin native compiler in the works that will support IOS, Android (native), servers, and WASM as outputs. This makes it a proper full stack language. Compiling to WASM to target frontend code is the sensible thing to do. As far as I can tell, Dart 2 compiles directly to javascript instead of using WASM. This does not make sense to me as a thing to push in 2018. Kotlin has one as well but they have shifted development towards their native compiler and supporting javascript vial wasm.