I think NEC PowerVR would be a good way to go. Since Apple and Samsung use them as well, it's likely a high volume product, so Nintendo could probably get a good price on it. Nintendo's worked with NEC many times in the past too. ARM seems the logical CPU partner, Nintendo's been using them for ages.

Something that maybe gives them 150-180 GFLOPs processing power on the go if its say a G6430 (dual core?), and doubles to 300-400 GFLOPS or more with a home dock (for TV play) would be solid.

So how would you place the two 3DS-screens on a 16:9-display?

90° rotated, upper screen with 800x480-resolution, lower screen with 640x480-resolution? In that case you would need a 1422x800-display and had a problem with the position of the buttons:

Upper screen with 800x480-resolution, lower screen with 640x480-resolution, placed side-by-side? In that case you would need a 1440x810-display and a lot of screen space would be wasted (again):

The best option I can think of would be displaying only one screen with doubled resolution and the other in its original resolution, the user can switch between zooming the upper and the lower screen. In that case a 1120x640-display would be enough:

For 3DS ports honestly I'd favor just going with a single screen option for as many games as possible since many DS/3DS games use the second screen for auxiliary features at best. 

But I think devs could offer different setups like side by side split screen or offer the user the option of trying different screen configs. Depends on the game.

How does Monster Hunter 3G Ultimate handle it when using the Pro Controller? 

I love the idea and many of the suggestions you have made. Personally, I would go more high-end. The idea that Nintendo can't sell at a high price is a myth. Wii could have sold at $400 a system at launch. The product just needs to be desirable.

I think a Nablet should sit at the top of the the Nintendo hierarchy at launch. It should look modern and high-end. I really like the idea of building it from the corpse of the Wii U, using much of the resources which should be able to be made portable in 2 years. It should be the size of an iPad mini and be essentially a true tablet with subtle circle pads, buttons and cross pads at each end. The screen should be of high quality.

With similar power and architecture, porting Wii U games should be quick and easy. The Nablet should launch with many Wii U titles available on eShop and some key games like Mario3DWorld and MarioKart 8 available at retail on flash cards. This worked great for past handleds, like the DS with Mario64. A few new, unique, non-Nintendo mascot games should also be out to push the system.

Market it as a high-end gaming product for adults who need a tablet. It should have it's own branding not unlike Wii at launch that makes it feel OK for adults to pick up (again like Wii at launch). The Wii Sports and Nintendoland team should be tasked with making lots of fun casual apps to play. If adults take to it, kids will follow. If it looks and works as nicely as an iPad, but also has cool games, kids will be wanting one in a hurry and it will quickly seem like a superior product because of the superior software. This will allow premium pricing, like Apple.

I would target a $299 price with a $399 XL model a possibility. A subscription service would be offered that allowed free downloads of classic titles remastered with modern graphics (quick-play titles like Donkey Kong in HD), online matchmaking and other cool apps for about $29/year. Wii U games would be available in the eshop for full price.

Nintendo's next home console would follow this branding and launch a year or two later and also follow the grown-up Nintendo theme to try and lure back those who grew up with Nintendo (like the Wii did). The Nablet could work as a controller or second screen for this new system like the Wii U pad does now. The subscription service would carry over to the new console, as would many games and apps. I would not target TV out with the Nablet, but rather connectivity with the new console to encourage consumers to become networked Nintendo homes with multiple products.

OP you make some very good points for a Nintendo tablet. Not sure I would prefer that over just using a Wii U, though. If I can get a Surface Pro with full Windows OS and a physical keyboard, why would I want another tablet when I already own Nintendo's current-gen console? Food for thought.

I think more and more I'm warming up to Stephen Totilo (Kotaku) and other's hypothetical console/ handheld Nintendo hybrid. Take it with you if you're traveling/ flying, and it outputs in 1080p to your TV with HDMI if you're playing on the couch. Of course, the main compelling reason for gamers to want this is it means a Nintendo platform that gets handheld and console games without having to buy two pieces of hardware. It also equals Nintendo outputting twice as many games. A huge boon for gamers. Since Nintendo would only be developing for a single, unified platform instead of trying to juggle a handheld AND a console at once. Since games keep taking longer and longer to make due to increased customer expectations and HD development, Nintendo would, hypothetically, no longer suffer from software droughts. But it only makes financial sense for Nintendo if twice as many people buy this hybrid than who bought their console or handheld. The install base would need to equate to 3DS and Wii U's lifetime sales for it to make sense. Otherwise Nintendo is losing an entire segment of the market. It would be expensive to manufacture, though, if it is lightweight, thin, and is capable of out-putting Wii U-level graphics with good battery life.

i don't.   think of the physics of this.  the torque would be horrible having the controls at the bottom.  it simply must have the buttons on the sides like vita/wiiU gamepad in order to be comfortable.

Absolutley.  And they shouldn't slide or snap out, just always be there in a subtle way, above or below the speakers.  They should also be able to be used in a verticle way for certain games or apps. And it must have a flat bottom to set down.

Anyone who is buying a tablet for their kid or something to play for themselves that has some solid games and buttons and does not want to spend $300-$500 would want one; I say this from some observations I made, a lot of parents I know rather than purchase a full $250+ console for their kids just got them a cheap tablet. Also, biggest selling apps (by a huge margin) on phones and tablets is games, so I think Nintendo can be a good fit in this space if they do try and make something inexpensive, decently powerred, with good multimedia and multitasking features.

I think a Nintendo gaming add-on for iPhone, iPad and select Android phones and tablets would gain much more market acceptance. Then add a few VC, DS, and 3DS games. And make it compatible as a wiiU gamepad. Do this all through a "nintendo channel" app of some kind. +1 if you can track existing eShop purchases, and have miiVerse built in.

It would be insanely profitable to manufacture. The brilliance of it is that Nintendo doesn't have to bear the burden of the cost of CPU's, memory etc. ... just provide the interface. I think that can help retain the authentic Nintendo "feel" and experience while pleasing at least half the angry mob who want Mario on the iphone.

Call it a half-step out of the hardware business...

Just ditch the controller and problem solved.