Well, DQ8 and 9 are some of the best performing niche JRPGs in the west, Last P5 PS4 numbers were 2-2.5M WW, while DQ8 did ~1.2M in the west alone. I think the series has done okay in the west even compared to that of games like Persona, Ni No Kuni, etc.
VGChartz has Ni No Kuni II at 870K, but it has well surpassed 1M units, but that's World Wide. While, Dragon Quest XI on VGChartz, which released far later than Ni No Kuni II, has sold around 500K units World Wide. And I'm sure digital probably isn't included. In Japan, Both also released on Steam, with estimates from ~100K-200K despite being released months apart. Xenoblade is actually less popular than it is in the West, so there's 2 sides to every coin.
I think a lot of people are waiting for the Switch version and when it arrives it will be among the best JRPGS on the platform, hopefully Nintendo fans bite. A while ago, it was noted that Dragon Quest XI has the best opening in series history in the west, so they're doing something right, they just need to keep going. Perhaps Smash will be the last chance it'll get to be insanely popular, but I think what it's doing now is passable.







