We maintain a roadmap for GIMP development that outlines the order of features to be implemented based on priorities.

The next big update will be v3.0 that will feature GTK+3 port and a lot of internal changes. For users, this will mostly mean: updated user interface, better support for graphic tablets, better support for HiDPI displays, better support for Wayland on Linux.

We are also opening the 2.10.x series for new features. This means you don't have to wait for exciting improvements for years anymore: any new feature can indeed be backported to a 2.10.x release as long as its code is not too invasive and making maintenance difficult.

All the new features from 2.10.x will be part of 3.0 as well.