They already confirmed long ago Endwalker was the exception because it was the conclusion of the Hydaelyn/Zodiark arc and Dawntrail would return to the ending at x.3 format.

Endwalker post-patch went from 6.1 to 6.5 because it was designed as a complete story arc for those patches. I think they can see the flaw, though, that that sort of format doesn't really allow for enough expansion set-up.