But Google is not pushing GWT anymore since a long time, they don't want more adoption of the framework, instead, they want you to start using Dart, so beware of GWT's future.
Google isn't pushing GWT sure, but it does have a dedicated GWT team and also just launched a brand-new product based on GWT. More to the point, based on the acceleration of the GWT community, it honestly doesn't matter how Google Proper cares about it. It's a stable and growing platform (e.g. http://gwtcreate.com)
Also, GWT has been open source since 2-3 years ago, and its development has been steadily going on. Even if Google was to abandon GWT, it would continue on being used & developed by others.