It does seem odd that they aren't at least showing off Pokemon Sun and Moon... Perhaps their focus on Zelda is an effort to really make a game people want that will soon be on the Nx?
It's been pretty clear either way that Nintendo has shifted most of its resources into the Nx library beginning, at a minimum, probably about 2+ years ago. They might be saving all of that stuff for one big announcement later in the year. They did, after all, say the primary reason the Nx is missing this holiday season is that they want to avoid the same small launch library issue they had with the Wii U.
One thing to keep in mind, though, is that the usual participants at E3 have been doing less and less each year, with some major developers dropping it entirely. While it was a useful tool recently in the reveal of the PS4/Xbox1, the importance of the expo has largely been on the decline for a while now, with big announcements often taking place at other expos and all of the content available on the internet rendering it, in some ways, almost pointless.
It's a fun event, but I think this increasing disinterest in E3 may be a portent of things to come for the fixture. Neither people nor developers/companies really need it anymore.







