The problem with Warfronts is that once you’ve done them a few times, there’s nothing new to do in it except repeat the same script over and over to farm for those awesome thematic armor pieces (and their super rare elite versions).
I had a thread with suggestions for Warfronts, and I think that Blizzard should have iterated more on them to make them more dynamic as the patches went on instead of doing heroic versions most people won’t do.
As for next warfront, I really doubt we will see one, unless 8.3.5 is way bigger than 7.3.5 was. But BfA has strayed away from the usual patch cycle formula, so maybe, if this time the real conclusion is not in the final raid, but on the patch after it, we may get a warfront alongside the finale of BfA. Who knows?
I’ll wait Blizzcon before speculating further.