I may be alone on this but I don't support the whole "both console and handheld into one" theory. First off, how is that convenient. I'll just have it always plugged into my TV or I will always be lazy and play it in my room.
Second, it prevents differences between games that work best as portable and games that work best as home console. If I'm going to play Pokemon then it's definitely going to be on a portable console because it's a game that can be used socially, to trade Pokemon for example and stuff. If I'm going to play Zelda Breath of the Wild how stupid would it be if I were to play it on the go. I'm supposed to admire the beautiful terrain and explore everything. That argument does break the whole theory that the NX might be a portable console in the end. But you get the point, some games don't fit as portable, and some don't fit as console.
Third, trying to make something that will work for both will just end up in a mess. Which is why there is a segregation between mobile and computer devices. Pretty much everything 12" and under is made for mobile software and games, while everything 12" and above is made with a computer display in mind (obviously, there are exceptions to this rule like the MBA 11" and the iPad Pro 12.9"). If Rovio made that Angry Birds was designed for a 480x320 iPhone screen, what do you think it would turn out on a giant 1920x1080 television? The HUD is going to be huge, all the buttons are going to be GIANT, ugh, a mess. Then let's take a look at something different, what if we were to have Splatoon work on the 3DS? It may seem simple, but I'll just point out that since I do not have an HDTV, I play it on my 480i CRT, which shouldn't be THAT much of an effect. However, the text is washed out and hard to read, a lot of detail is hard to notice, and everything just looks kinda awful. Okay, playable, but awful. If we were to directly pull the game onto the pathetic 400x240 display of the 3DS, it'll look downright disgusting. And even IF we had a 1080p display on our new 4DS or HDS or NX or whatever, then everything will look tiny. If
this is the future of gaming in your opinion, then good for you. Which brings to the point that if everyone would have to make the game twice, it's going to be awful and expensive. A stupid idea. A VERY pointless idea.
Fourth, I don't think you realise how little can a cheap portable device handle in terms of power. The successor to the Wii U will probably be as powerful as the PS4 and Xbox One, probably a bit less. That's for a device with a theoretical price of $300 and that sits on a desk. The 3DS is roughly the same power as the GameCube, and cannot emulate this nor the N64. With this in mind, its successor would probably be as powerful as the Wii, which itself is PS2-level power. So can you place a what today needs a console the size of a Mac Mini, inside a device that is not more than a centimetre thick, while keeping the low cost of $300, LET ALONE keeping the general cost of $200 for a Nintendo-branded handheld? NO. You can't. This is not an iPhone. Keep dreaming.
Fifth, and this one is the most important. It's the STUPIDEST business decision Nintendo could make. Why would they combine two systems into one, therefore allowing people to only pay for one console? The DS family sold 150M and the Wii sold 100M for example, if they combined them both, do you really think they would have sold 250M? I feel like it would sold more like 30M. 10M if it costed like an iPhone. This crap is alienating to customers and is stupid as well, the only reason I bought a Wii U was because of its games. If everything I could play on the Wii U only would be available on the 3DS, I'd have no reason to buy one.
I see only one future, it's we get an HDS or something similar in 2017, then we see the successor to the Wii U in the following years. Think logically, not one-sided.
