Tumbleweed 20160613 snapshot will be the last snapshot to be based on GCC 5, according to the openSUSE Project’s Dominique Leuenberger.
GCC 6 will become the new default compiler, but the release date of the snapshot is difficult to predict right now because Tumbleweed is competing with builds allocated for the next Alpha 2 release of openSUSE Leap 42.2, which is scheduled to be release next week before the openSUSE Conference.
Some fixes in the GCC 6 snapshot will likely be needed, so users should pay attention to the openSUSE Factory Mailing List for any fixes that might be necessary.
Help Test Alpha 2 Release
As for Leap 42.2, a lot of focus was made on systemd and GNOME for the Alpha 2 release. Once Alpha 2 is released, we encourage people to test it and get involved with the development on the openSUSE Factory Mailing List.
View the road map for Leap 42.2 releases at https://en.opensuse.org/openSUSE:Roadmap.