I'm betting its a home console. I also think that Nintendo will leave handheld gaming altogether after 3DS and use mobile game development to steer customers towards the NX console. The NX console will play both their mobile games and NX games. There is the 'fusion' concept and explains why they are secretive about it. Leaving the handheld business for mobile would kill all sales for N3DS.

Like others have said, NX was described as "dedicated game platform".
It's different from the infrastructure Nintendo is preparing.

Also, it no longer makes sense to announce a console one year and release it the next. Specially in Nintendo's case.
We all saw how announcing and releasing both the XB1 and PS4 helped maintain the hype for those consoles.
The next Nintendo really needs that.

Not to mention that with Wii U sales so low, if they decide to announce it in 2016 and release it in 2017 the console simply won't survive that long.
Announcing it and releasing it in 2016 is the best choice - probably the only real choice - for Nintedo if it wants to keep whatever momentum it has next year. Because, from this point onward, Wii U just won't get the support it has had up to now.

The only problem I have with this is that it still doesn't make sense to me for Nintendo to kill the only division that has consistently made them money. I mean, their handhelds have been the definition of printing money from basically the Gameboy through the 3DS, sans the Virtual Boy, as much of a handheld as that could be considered. Canibilizing their handheld division to try to boost their console division feels like the equivalent of Nintendo putting the business knife in their company stomach, ready to commit company seppuku at any given moment.

I honestly don't know what to think anymore. Nintendo is in a pickle or how the saying goes :P

It would be the most practical thing. They won't have to develop hardware for a handheld that will be outdated instantly in a mobile world. Think about it. The handheld will need to be around for maybe 4 or 5 years at least. During this entire time, mobile hardware gets more and more powerful while handhelds stagnate instantly after launch, unless they refresh hardware like N3DS.

However N3DS games fractures the user base and even infuriates some users. Plus developing games for it and only it isn't practical. But as a mobile platform, the games would be around for years, and they wouldn't have to waste millions developing instantly outdated hardware. They will already be in the hands of hundreds of millions of potential customers from launch. Then all Nintendo needs to do is steer those customers towards the NX console which will not only play all their favorite mobile games, but tons of great high end games.

Yeah i agree with how Nintendo should leave the Wii brand, but its the matter of when. Releasing early in the generation might not increase much sales, like how PS4 and XONE owners might not be ready to buy another console, since their console is still new, and getting the latest games. Nintendo is in a very tough position right now to CONVINCE both gamers and developers why they should buy and make games for this NX. 

I've said Nintendo should just let people choose what they want. Too much money/energy wasted in trying to dictate to people rather than offering them choice. If I don't want a purple sweater, stop trying to sell me a purple sweater, you're just wasting your time.

NX hardware = Mobile (as in smartphone/tablet sized) ARM + AMD system on chip. This SoC scales waaaay up and waaay down. Incorporates elements of the Wii U architecture.

From this you can have

NX Tablet = 400-500 GFLOPS, 7-inch LCD.

NX Handheld = 400-500 GFLOPS, 5-inch LCD, fold out design.

NX Family Console = 400-500 GFLOPS, super cheap (sub $200), comes with wacky new controller for family fun.

NX Pro Console = 3 TFLOP. Runs demanding games in 1080p, and even simpler games at 2K resolution. $349.99 MSRP.

If one model isn't selling great ... just phase it out. Most games run on all four devices.

I used to think the "Family Console" could be 1TFLOP, but now I'm thinking maybe they should just make it super cheap and let it act as a very cheap way for someone to get into the NX ecosystem on a whim, and then boom, now you have them stuck in your web, lol. 

It would kill all sales, in general. No one would be able to sell full $40 games on the platform.

In fact, reading it again, Iwata confirms it's new hardware: "Nintendo, together with DeNA, will jointly develop a new membership service which encompasses the existing Nintendo 3DS and Wii U systems, the new hardware system with a brand-new concept, NX, and smart devices and PCs, and Nintendo will be the primary party to operate this new membership service."

The problem here is too many options. Most consumers are not educated to the degree that those of us who dwell on video game hardware related forums may be. I mean, one slightly confusing name, and some consumers in 2015 still don't understand that the Wii U is different console and not just a tablet controller addon for the Wii. Consumers like having a pretty clear choice. For example, they like Sony. Sony made the PS4. They buy a PS4. They may have a decent understanding of memory and eventually opt for a console with more, but that's a minor difference that's unlikely to confound the user. Your suggestion means shopping at dedicated game stores like Gamestop will be a nightmare everytime a consumer is even slightly confused about this proposed NX family of systems and has to have it broken down for them. Then they still won't understand and will just buy an easy to understand competition console instead.