Yes, sure and I'm sure Iwata would have been thrilled with the news.

Look Nintendo doesn't often allow other companies to circumvent their own PR process, but Dragon Quest is a big deal in Japan and I'm sure Iwata would have understood that very well.

Besides it's not like Square-Enix took away anything from a proper NX unveil ... we still know next to nothing about the system(s). If anything S-E just added more excitement to the mix, and if DQXI is already on board, then it will make Nintendo's job in recruiting other Japanese third parties at least that much easier. 

LOL if anything this give us hope the NX may have some great support at launch since it wasn't 100% confirmed but rather may do an NX version. So Nintendo must have done something right with it to convince some people to consider it.

The only unknown is what version of the game the NX will run.