The Vita is a really nice piece of kit, just bad timing all around. The mobile processors of today like the A9 are so much more powerful just a few years later.

I'm excited what Nintendo can do with the 3DS successor/portable NX. I think they're going to be able to get a wicked powerful little beast of a machine even at $200 if they want.

I priced out what a Nintendo portable might cost using IHS just released iPhone 6S Plus component costs

http://9to5mac.com/2015/09/30/iphone-6s-plus-teardown-analysis/

$42 - LCD 6-inch 1280x720 touch panel (iPhone costs $52, but it 1920x1080 and a very high quality display)
$35 - AMD custom 14nm system on chip (vs. Apple A9 processor which costs $22)
$17 - Motion sensors, gyros, NFC chip, WiFi chip (iPhone is about $23 for these components, Nintendo usually goes cheap)
$8 - Battery Pak (iPhone 6S Plus has a $4.50 battery, but we need a bigger battery for gaming)
$26 - 3GB LPDDR4 RAM (iPhone's 2GB is $17, but prices will be cheaper in a year)
$4 - Cameras ($20+ on iPhone, but Nintendo cheaps out here)
$25 - Misc/Electro-Magnetical (iPhone is $40 but they use higher end metals, glass, more premium materials, Nintendo doesn't need that).
$4 - Box Contents
$4 - Manufacturing Cost

$5 - 16GB NAND Flash (could be 32GB by next year with dropping costs). 

I'll even throw in a $10 Retail profit margin ... still only $174 and this device would have a processor more powerful than the Apple one ($35 set aside for the main SoC vs. only $22 for the Apple A9).

Throw some Android app functionality there, Nintendo games, Monster Hunter, Dragon Quest ... wouldn't be bad at all. Would be a massive step past what the Vita was.

I agree that NX handheld needs to be at least strong like Vita, but probably will be stronger, better CPU, better GPU and probably 2GB Ram. My point is even in today's standard Vita has weak hardware Vita games are still looking very good.

Nintendo should not accept anything less than a processor that can not only give them Wii U quality graphics in a portable.

That should be the minimum so that they can easily port over their Wii U engines and have a seamless transition into the NX product cycle. There's also several Wii U games that really deserve a second release on the NX to gain more sales and be played by more people. 

In fact I would target even above that ... the ability to run XB1 ports at 960x540 resolution (1/4th 1080P) is what I would personally aim for and by 2016 I do believe this will be possible to achieve. 

How much energy would that take? A portable device would recquire at least 8 or 9 hours of gameplay at its maximum energy consumption. If it doesn't reach it, it might as well be always attached to a plug. What's the strongest mobile battery in the market today?

3DS and Vita run for 3 1/2-4 1/2 hours generally, so 8-9 hours for a game handheld hasn't been the norm for like 5 years now. An iPad also craps out while gaming after about 4-6 hours. 

The good thing about batteries are they are relatively cheap. The downside is a huge battery will require ... well a larger form factor most likely (would likely need to be a tablet style device). 

It'll be interesting to see how Nintendo plays it. This is one of those cases where I really do hope I am wrong, and Nintendo finds a way to carve out a sustainable interest in their products. From my point of view, however it is not looking good. The NX could very well be the last piece of hardware Nintendo puts out if they screw this up, and that would be a game.

If the portable NX (*portable*, not the console, devs don't give a walrus' ass about Nintendo consoles and aren't going to be interested in a second "late to the party" console in a row) can run decent versions of XB1/PS4 engines ... that could be a game changer for Nintendo.

They would get a lot of developer support if devs could port their current gen games rather than having to make something for Nintendo portables from like 2 generations behind.

This is a GT730M mobile (lap top) processor running Assassin's Creed Unity (a PS4/XB1 only game), it's about a 500 GFLOP part, and it runs the game pretty nicely from what I can see. 1280x720 resolution, V-Sync on, high texture setting, FXAA anti-aliasing, etc.

https://www.youtube.com/watch?v=L7o4l1NEoxs

The higher end PowerVR mobile processors are supposedly above the GT730M.