I have several reasons to believe that(such as some known game releases in 2016) but I remembered a  long trend...

The dolphin(codename of the  gc) was teased in 1999(third year of n64),was announcend at E3 2000 and it released in november 2001,Revolution(codename of the wii) was teased in 2004(third year of gc) was announced at E3 2005 and released in november 2006,Nx was teased this year (2015,third year of wii u)Announcement at E3 2016?Probably as ninty said that we will get details for it in 2016,release november 2017?

Also,Project cafe (codename of the wii u)may not followed this trend obviously because wii was selling tons of units but partially it did it since it was announced in E3 2011 and released in november 2012,i.e an announcement in E3 and a release one year and half after of it,So that't a proof too!The only difference is that it wasn't  teased in its predecessor third year but in the 5th of it(It's apparent why,wii was a beast) and  in the year of its announcement at E3...

January 1st - March 20th is winter 2017...

Ooops,lol I forgot that november is a month of autumn...

March is the first month of spring even though winter techically ends on 20th Of March,one day before the spring equinox...

Just say holiday 2017

Okay but only in the title!:P I had the word winter 5 times and change it with November,I'm bored doing that again with November->iin the  holidays!:P

If they wait longer for the release after the reveal it will hurt Wii U sales more, as soon as they announce it  potential Wii U owner will turn their head per-ordering the console, and also big store will also start to make per-ordering. Nintendo also evolving and  will follow new standard, if they can release it sooner then they will do it and i think today standard of social media marketing is help market and advertise the product and also infrastructure to make it is available . But there is a possibility the new platform will be release on 2017 but then again it will just make difficult for their console sales  performance.

Makes sense to me. I also think that they will have more games coming up for the wiiU through out 2016 while having much less for the 3ds from Nintendo. On top of that, they would want to keep the handheld momentum going instead of just letting it die before releasing their next gen one so it makes sense imo

Well revolution(codename of wii) tease in early 2004, didn't stop gc to sell another 7,17m units 2004-2006...

Although gc had a price drop of 50$ in 2002 and another one of 50$ in 2003,and sold fast so in 2004 the effect was moderated considerably but still had a satisfying impact on it's sales...If wii u doesn't get a price cut this year,your anxiety will be justified!:P

Trends, patterns, whatever you wanna call it can be broken, but yeah I'm expecting 2017 aswell. Still gotta give us Animal Crossing and Paper Mario afterall!

I was thinking that I had included that as a secondary reason in my op...:P
Some of them  in 2016,Zelda U,SMT x FE,Pokken fighters?Something else unannounced(Animal crossing U,paper mario U,maybe a luigi's mansion U e.t.c),there is still space and time...

P.s The people who will castigate me are propably sleeping,ZG,SWE,SPM...e.t.c  ;)