So the next Dragon Quest, DQXI, is for 3DS, PS4, and NX, confirmed. Sounds like each version kinda runs on its own engine:
Masahiro Sakurai: Well then, I would like to ask about each of your new games. First, Dragon Quest XI. The 11th installment in the series will be released simultaneously on Nintendo 3DS and PlayStation 4, and including NX it’s coming out on three platforms, right?
Yuji Horii: That’s right. The use of hardware is different for each system, so it’s quite a challenge.
Also this:
Horii: That’s right. There are a lot of difficulties because of that. Each one has a different look to it, and there’s also a PlayStation 4 version, so if we make a small fix then we have to fix it across every version.
So now officially, the NX's confirmed game list is Zelda: Breath of the Wild, Dragon Quest XI, Dragon Quest X, Sonic, and Just Dance.