Significant effort is being put into Flutter as well as Dart 2, probably why you haven't heard much news lately.
Angular Dart is pretty mature as well at this stage and we've been using Angular Dart since its beta release.
Dart itself we've been using for all frontend work since version 1.0
Dart is currently #23 on the Tiobe index, so it's just 3 spaces from the top 20 which is not bad.