So much talk about the NX "console" and the Wii U (a system with a paltry 12 million users) ... why no talk about the 3DS successor?

The 3DS is past it's "5 year age" in a matter of weeks (launched in Japan in Feb 2011) and Nintendo has pretty much exhausted every possible franchise for it. 

3DS successor is far more vital to Nintendo than NX (if it's a discreet console) or Wii U, that's just a fact. 

If the 3DS successor continues to suffer declining marketshare due to kids being raised on tablets/phones these days, then Nintendo's hardware future is pretty much kaput, doesn't matter how fancy-schmancy a console NX is or how long Nintendo decides to support the Wii U. Even if NX is a unified platform, realisitically the portable model is going to have to carry like 80% of the load most likely given Nintendo's crap track record with home consoles. 

I just find it funny that the portable is always swept aside like "oh yeah, Nintendo maybe will throw out a handheld this year" like they can just fart one out as a side thought. 

Because the popular theory is that NX is both a home-console and a handheld

Maybe because we know practically nothing about it?

What 3ds successor?

That simply isn't true. The NX is either going to be the final nail in the coffin for Nintendo in terms of relevance to the gaming industry, or it'll be their saving grace. In the end, nothing can change consumers moving more towards smartphones for entertainment, but the console market is going to be there, and that's where we need to see some major improvement from Nintendo.

Nintendo has mentioned Mobile alot lately....

Either that or NX is actually both a homeconsole & and a handheld, that play the same games.
(so when the NX launches, 2 models will launch at the same time, one of which will be a handheld)

This, basically. Don't you think if such a thing were announced, it would be widely spoken about?

cause we all know it will be the best selling handheld.. By default.. Kinda boring for a sales site

It's hard to talk about something that hasn't been announced/teased compared to the NX.

Because
a) the common thought is that NX is the name for both the Handheld and the home console;
b) 3DS lineup for this year is full of games FOR THE FULL YEAR, while the Wii U lacks anything in the 2nd half of the year besides Zelda;
c)Mobile is stronger than in 2011, a new Nintendo Handheld could start struggling in the market unless they make something compatible with smartphones/ A smartphone;
d) most people here discriminate handhelds thinking they are not consoles imho :v