The San Diego Comic Con is starting and Blizzard seem to be extra invested in it this time.
Could a new expansion be revealed next week?
We've almost defeated the Legion and its time to move on from the Hellfire Peninsula green shit and barren wasteland type areas. Many people are sick of it by now.
Legion itself wasn't reaved at Blizzcon so there definitely is a chance. They could even introduce it being a comic-con and primarily a written medium, they could even reflect on that and announce it via a letter from the forces left behind on Azeroth which came to the faction leader's attention, on that of an ancient evil is rising from the oceans while they were on Argus or something like that. That would be a fun change from all the old announcements.