DQ doesn't cater to the Western audience. I honestly don't know if a single DQ game has been designed with any intent for it to be localized elsewhere to begin with. DQ is not a popular series outside of Japan. That said, it has also sold well on home consoles in Japan for the past few offline main installments. I'm sure they're sticking to home consoles here. I think DQ IX was a one off because they didn't feel any of the home consoles were the right fit for a DQ game at the time (that, and I think DQ X had already been in development as a console MMO).
true. DQ9 is with 3Ds which has a large fanbase. DQ8 was under PS2. If it is into a home console i believe Square Enix would use both Wii U and PS4 as the installbase is really not that big opting for PS4 exclusive would hurt their sales. but if it is really more about money, SE would pick the both handhenlds over hc.