two more please!!!

It could be, however the "reveal" next year could be just a brief reveal, rather than details, release date, etc. If "NX" is indeed anything like the "Nintendo Fusion" idea I would guess 2017 release, or perhaps the release of the handheld equivalent only in 2016.

I think some people are reading too much into them "announcing" a new console, with regards to how it affects the state of the Wii U. It was a response to the announcement of putting games on mobile, to reassure that they plan to remain in the console business. If Sony or Microsoft took a big step that made people think they were moving into streaming games or PC only in the near future, they would likely state that they "are still working on the next Playstation / Xbox", but it that wouldn't be cause for "Sony giving up on PS4, already planning PS5!!"

I think NX is the 3DS' successor

Pretty much this. And the fact that they already said new infos will only follow next year, which means the release would probably only be in 2017.

how do you know its a console?

This is right, E3 2015 will be the last E3 where Nintendo focus on Wii U.

No. The Wii U was released six years after the Wii, and it hasn't even been two years and a half since Wii U's release. We'll see at least two more Wii U-focused E3's.

It'll start to dip in 2017

Since I am in the camp that the NX is a handheld to show "Hey! Just because we are making smart phone games, doesn't mean we aren't still making a dedicated handheld device!" so to quote Aigis "Nope, I say Nope to this."
E3 2017 may be the last Wii U E3.

I think so. I really don't see Nintendo coming up with much of a lineup for Wii U after 2015. 2016 will be their "limp to a new console" year, like 2001, 2006, and 2012.

More to the point, it's not worth it for Nintendo to put good money after bad. 4 years will be a fine timeline for a console that sold as poorly as the Wii U. 4 years were all Xbox got, after all, and few people cried foul.