https://www.gamespot.com/articles/dragon-quest-11-switch-coming-much-later-3ds-not-a/1100-6457756/

Dragon Quest XI finally has a release date on PC and PlayStation 4, but not all the news is rosy if you prefer your RPGs on Nintendo systems. Square Enix has indicated that the Switch version may take quite a while to arrive in the West, and the 3DS version simply isn't coming at all.

In a statement to IGN, the company indicated that the Switch version is still in development for North America and Europe, but that the developer still has "a long way to go until its release." A representative reportedly said a Switch version definitely isn't coming in 2018, and could be much later. The company seems to suggest there are technical reasons for the port taking significantly longer.