GWT’s roadmap is planned on Github using Github Milestones. Milestones will cover the next releases and because priorities can change please check milestones directly on Github for all the details.
As a high level goal next releases of GWT focus on bringing Java language features as well as JRE emulation up to Java 21. Additionally GWT explores support of some J2CL exclusive JsInterop features in GWT compiler.
The GWT SDK is Open Source. So, we are always looking for contributor or / and sponsors. If you are willing to contribute, feel free to contact the GWT project team using our Elemental chanel. Donations can be done via Open Collective.