Update:
In a curious turn of events Square Enix is now claiming that Nintendo NX versions of Dragon Quest X and XI are only ‘under consideration’.This wasn’t the line coming from the initial announcement, and it’s unclear whether something was lost in translation or whether Square Enix has actually shifted its position – perhaps after being contacted by Nintendo.
It seems inconceivable they could’ve made the announcement without first checking with Nintendo. But it also seems equally unlikely they’d throw the idea of NX support out as a vague idea they hadn’t fully thought through.