At least in legion there was one more major content patch after people got flying, in BFA it seems like Azshara raid is the final raid of BFA. There is no hint of anything beyond 8.2… Flying does not add to this expansion at all, there is no content that was designed specifically for flying. Legion had just 1 reputation required now BFA has 2 for pathfinder 2. This kind of trend just points to Blizzard not interested in the value of flying with exception to tying massive time sinks and soo many quests to unlock it.