I have worked over GWT and GXT for some time now, and as a developer I can say that - GWT/GXT based application are fast for UI development once the layout is done , and they are easy to debug also, there are so many libraries available - which are compatible with gwt and are free also , well there may not be that much of future release in gwt/gxt - but i think the versions of gwt/gxt which are available are powerful enough to develop a complete web application easily.
By the google trends , what I have got for GWT is as below -
and for GXT
If you see the trend for GWT and GXT near by end of 2018 - it has been increased a bit
If you dig into stack-overflow - you will get ton of questions and response around GWT and GXT
GWT questions
GXT questions
so i think - if you have team of good developers - who already have knowledge on GWT / GXT - you can go ahead -
All the best :)
As a I was always fond of GWT - i kept following for updates in between and here you go, new release of GWT is here
[GWT release-notes][5]
2.10.0 June 9, 2022