I don't see how a quality expansion can be released given the timeline Blizzard has to work with.
There is at most a few months left till the Beta. By then:
- 36 specialisations have to be finalised
- 10 dungeons tested
- 6 zones tested
- raid testing starting
All this on top of the new systems coming with BfA:
- warfronts
- islands
- PvP overhaul
- stat squish
- AP 2.0: Azerite
How in the world is there enough time to fully flesh out these systems in a few months so they can be fine tuned for Beta? I think that Blizzard has once again bitten off more than they can chew and as a result BfA will be rushed out in order to meet thr September deadline they cornered themselves into.