I won't say that it WON'T launch in late 2016, I just would be somewhat surprised if it did. It would be folly to pull a Saturn/Dreamcast deal, and rush it out because the Wii U isn't selling amazing numbers. It isn't as if they aren't making money off of Wii U, they are. Just not anywhere close to what they obviously would LIKE to be making.
I think Wii U, especially because of it's thriving eShop/Miiverse community, can sustain for another year and a half to two years. They need some more retail titles, which is fair, because we know more is coming, such as SMT x FE, such as Devil's Third, Zelda, Retro's project, Next Level's rumored Wii U title that wasn't revealed, etc. There are still other studios, internal Nintendo ones, as well as outside partners such as Monster Games, that obviously have projects in the works that they're not talking about yet.
So I do think we'll see some good games beyond Zelda next year. I think they'll reveal "NX" (or rather it's real name) at E3 or thereabouts next year, try to blow people away and possibly make up for the "meh" showing at this year's E3 (it WASN'T awful....just not exciting). And that the system itself will launch sometime in 2017. That makes the most sense to me, it allows them time to squeeze some more life (and cash) out of Wii U, and it gives them much more time to actually do what they stumbled doing with Wii U: take the time to MAKE SURE plenty of games are ready for it.