Just watched this great presentation from @AdrianVovk at the @allsystemsgo conference:
https://www.youtube.com/watch?v=uCAlzx_x6rY
It covers the migration to Wayland-only, and of the @gnome session to systemd, eliminating tens of thousands of lines of ancient C code (often a quarter to a half of the codebase depending on the module) and providing more featureful session handling, including session saving and processes suspension. The remote desktop implications are interesting too.