I just wanted to call out in particular this bit from Jan's note:

This slip of the F26 release does not have any impact on F27 schedule [3]. [3] https://fedoraproject.org/wiki/Releases/27/Schedule

This means that system-wide changes for Fedora 27 should be submitted to FESCo *before* the Fedora 26 final release. Changes which require a mass rebuild should be in _this_ month.