As we know, the reason Iwata revealed the existence of NX so early was to assuage fears that Nintendo no longer was going to make dedicated video game hardware--but that was nearly a year and a half ago, and I can guarantee you that the press's (and general public's) main takeaway from that March 2015 day was that Nintendo entered the mobile games market.
Fast-forward to the Apple event, and we got Super Mario Run, which many consider to be Nintendo's first all-in mobile game (not counting Pokemon, since Niantic / TPC handled that one). Again, we see Nintendo receiving massive press and general public attention regarding entering the mobile games industry -- but this time, no NX announcement in tandem to assuage the fears that Nintendo is exiting dedicated games hardware.
I feel that if Nintendo wants to keep its software-driven dedicated hardware business as the core forefront of its overall model (which Kimishima's "Message from the President" on Nintendo's investor relations website still states is the case), then they should talk about NX very, very soon. Hell, I've got some friends who casually play Nintendo games starting to question the existence of NX at this point; that can't be good for the core of their business.