I just read the report about the future of GWT, really good job done by the GWT Steering Committee. You can get your free copy from the report here:
I was actually surprised that there are not a lot of organizations using GWT for building portlets. I personally know several and I was involved to develop GWT Portlets few times as well. I suppose that most of this organizations did not post to the survey or they just select business applications instead of portlets, which I can understand. The portlets are mostly applications for the business side in the organizations. Your usually never sell internally in the organization portlets but business application and the business does not really care what it calls, they want to have the functionality they require and pay.
Later the Committee will post the wish list here:
but I think I can guess that the compiler optimization will be on the first place.