This, at least for me, was an extremely weird move. It's not a totally impredictable one, since people pointed out some reasons before (3DS not being as sucessful as DS, Wii U flopping in all it's lifetime, PS4 being sucessful in the west even having a hard time in the Japan), but it's weird if considering that the 3DS had basically two DQ remakes prior the XI announcement. Why try to build a fanbase of the series inside the 3DS if they, at least in the beggining of the development, didn't had any intention on putting DQ11 on it? Wouldn't be easier to just remaster DQ8 for PS4?
About DQ 12, if they ever skip Switch and went full force to PS5, the only logical explanation on my mind is that they want to syncronize and parallel the Dragon Quest fanbase with the Final Fantasy fanbase and unify them into one console brand. It's probably the most stupid way to treat two different franchises with so little in common, but it's not the most impossible move ever for Square-Enix.
About Nagoshi and Switch being for Kids and Teens, knowing that the Yakuza series always gave me an impression of being a light-heated parody of the Real Yakuza, this kind of statement coming from him is a little ironic.