It looks like Google doesn't want to push more developers to GWT, instead they want devs to use Dart and Polymer, if you check the bottom of this link https://developer.chrome.com/home GWT is no where to be seen.
Just saying that GWT might not a have good future.
Google is a big place; Dart and Polymer are funded as products under the Chrome division (that has budget to spend on big teams and marketing and developer advocates like Seth Ladd).
GWT is under the platform/languages team, e.g. the same org structure that manages Google's contributions to, say, GCC.
So, right, it's not surprising that there is not a lot of marketing pizzazz around GWT, but I don't think that fundamentally affects it's future viability.
Frankly, I'd be much more surprised to see Dart go away than GWT: a) GWT translates to JS, which will be here forever, and b) there are literally 1000+ projects (both public apps and LOB-type stuff) inside of Google that use GWT.
If Dart can't get over the hump and truly become a first-class citizen, eh...
Just saying that GWT might not a have good future.