I do thick we'll go back to Cantha eventually but don't think so for next expac (maybe expac 4 or 5), since we just had a human centered expac and two LW seasons. I would rather expect the Charr homelands/eastern Ascalon next since we haven't gotten much lore on Charr so far and based on the recent map updates and expansion in those regions. Second most likely area for me would be the Unending Ocean if they decide to go for an underwater expac with Bubbles, since it makes sense storywise to deal with it next, but I would still expect a LW season or two before that, so maybe if that's what the next LW season is about.