I think they have hinted about it as a possibility before. The problem I'd have with it, really, is that we have had a "Japanese-themed" expansion called Stormblood with a "Japan-style" place called Kugane and Samurai, and I wouldn't be enthusiastic about a repeat. I had to try hard to enjoy Stormblood and was able to but it was due to knowing that future expansions wouldn't be themed like that.

I think that other places are of greater interest to the community anyway. They know that Meracydia is on everyone's radar and they are evidently going down Emech Selch's list. They have strongly hinted at G'raha's home area of Corvos around Ilsabard, and Y'shtola's pursuit of other shards. Given how long expansions take to make and subsequently last now, that probably covers most of the next 10 years.