I realize that the major point of GIMP 3 is the port to GTK3. That said, I feel like colour spaces are what people have been waiting for and probably the most significant deficiency that keeps GIMP from being treated as a professional tool.
If they are really this close, why not set the GIMP 3 release date for when colour management is ready?
Non-destructive editing will be huge as well. GIMP 3 is really going to be a crazy leap forward. It is going to be amazing to finally get access to all this work that has been walled off for decades.
The bug situation sounds terrible. Honestly though, they should just get 3 out and then make bug fixing the number one job until it gets into better shape.
Not only is it a small team but right now there are basically two different projects ( 2 and 3 ). With only one code base, perhaps the pace of progress can improve.
Hopefully the move to GTK4 is easier.