Honestly, I think you should include Sun and Moon, But I would not include it in the main patch. (And I most definitely would not post pone the patch because of it), Besides, gen 7 was just newly announced and won't be released until the holidays. So doing it now, or waiting on it wouldn't be that great, also concerning the fact that you'd have to waits... probably a couple of months for the sprites.
So, In my opinion, You should include sun and moon, but you should release the 721 patch first, and release a new patch (But still the same base, so that way its compatible) whenever sun and moon are released.
Anywho, I know you are doing a good job, If you don't mind me asking, what's next? or what's left to do in the patch? You've done all the Pokemon, My best guess is probably items?