Anything but this horrible "Fusion" idea that people have been throwing around in the forums. I like my consoles how I like my food; separate and not "fused" together.

It would be nice if they could incorporate two thumb pads without making it as stupidly long as the PSP/Vita. They need to also extend the battery life by quite a bit. I want them to really focus on that and get it right like they did with the Lite.

Also, 2017. I expect them to announce a new Handheld at E3 2016 and then release it around the same time they did the 3DS.

Nintendo abandons two screens and replaces them with one 1280X720 display. They keep the spirit of the DS alive however by placing this screen sideways so that it resembles the 2DS, just without the divider. This allows devs to manage the screen space with more freedom. Maps, HUD, and menu elements can just take up the bottom half like they traditionally have, or they could go crazy and put some menu elements on the bottom fourth and some HUD elements on the top fourth with gameplay in the middle.

The rectangle on the back of the device is a touchpad, similar to the rear touchpad on the vita. Devs can manage it however they want and incorporate someof the great uses found on Vita. R2 and L2 can be done with the pad, as well as analogue input by sliding up/down. Both it and the screen are capacitive with multitouch capabilities. This new handheld also features two circular pads, six-axis motion, and eye-tracking using the cameras (not shown).

The system menu is accessed by sliding up at the bottom edge of the screen, similar to some modern smartphones. This devices UI supports multitasking between apps, as well as remote play of most Wii U and Wii U 2 titles.

Power wise we are looking at something a bit weaker than Vita, but it makes that up by only being $149. Announced next E3 and releases early 2016.

First of all, I want the next Nintendo handheld to cost $200 at launch. If this means letting the 3DS rule the market for an extra few months or even a year, so be it. The3DS taught us that an earlier expensive launch is not necessarily a good thing.

Timing

• If this thing comes out before Holiday 2016, I'd be disappointed. I'd like my 3DS to be the focus of handheld development for five solid years.
• That said, I recognize that conditions aren't as favorable to the 3DS as they were to the DS before it.
• Therefore, I hope for a Q4 2016 to Q4 2017 launch for the "4DS."

Hardware

• Keep the basic form factor of the DS and 3DS families: it's familiar and it works well.
• The top screen should be a lower form of HD ala the VIta, perhaps something like 960 by 540 pixels, with the lower screen being 720 by 540. True SD visuals wouldn't be a deal breaker though, especially considering the fairly high pixel density it would still entail.
• Other than a second analog stick, all the basic buttons are already there. I'd personally combine the Power and Home buttons and move Start and Select somewhere more convenient, but the basics of the 3DS control scheme work.
• Keep the 3D top screen, but also try making it double as a touchscreen if possible. People like smearing fingers over screens nowadays.
• In terms of horsepower, I'm thinking no more than twice the power of the Vita.
• Compatibility with every SD Card under the sun is a must, as is backwards compatibility with at least the 3DS library.
• Games ought to be available on 32 GB cards, similar to the 3DS's 4 GB cards. That's big enough for the next big Portable epic.
• Besides that, a better battery life would be nice, as opposed to OLED screens.

Features and Software

• Multitasking capabilities on par with at lest the WIi U is a must. This means easy web and Miiverse access from within a game, preferably without having to go to the home menu and enter a password or some **** like that.
• It might be much to demand Wii U cross-compatibility, but the Wii U's sucessor whould be built closely alongside the 4DS. This means crossplay and the like.
• Some better apps than the 3DS has for services like Netflix and sites like YouTube would be appreciated.

Games

• I'm going to assume a "sometime in 2017" launch for the 4DS here. Let's say exactly six years after the DS.
• Q1: Super Steel Diver: The version people care about, Mario Kart 9
• Q2: Mario & Luigi 5, Kirby's Epic Yarn port
• Q3: Advance Wars Reboot, Kirby platformer/spinoff. Luigi's Mansion 3: Sinister Spectres
• Q4: A 3D Super Mario Game (Possibly a 3D Land successor?), Some new Zelda game (a 3rd LttP setting game maybe? Or maybe a spinoff of Zelda U.)

That all sounds glorious but too good to be true. If it's real, and were to release with Pokemon; it would take the world by storm. Also, with the names Plus and Minus the games better give you a gift Plusle and Minun respectively.

This seems FARRR too good to be true, especially this early on. I mean imagine going from the 3DS to this...

I'm liking the 2016 launch though.

HDDS (High Definition Dual Screen)
I think its now safe for them to make a hd version of a DS
The specs may be either as good as a vitas or a little weaker than it (i dont see them making an overpowered handheld) . Possibly a 2015 reveal with a 2016 release date
It will still use sd cards and catridges like 3ds, support nfc
I dont think it will support any sim cards, just wifi
2 analogs or it will have 2 versions, one with a single analog stick and one with dual sticks (thats a slim possibility)
Powered by android for apps? (VERY slim chance)

This is from a not handheld guy. Let's see

• Bigger buttons/d-pad (that's my biggest drawback with handhelds)
• One, 720p and reasonably big (5" like the 3DS XL) screen.
• Also about the screen, no 3D effect but multitouch.
• Better/longer autonomy.
• Dual analog sticks/circle pads.
• Same architecture (not specs) as Nintendo's next home console (something hinted by Nintendo themselves)
• The last 2 points would make possible to play its games on the TV through the next home console and use the handheld as an extra controller for the home console.
• A better strategy when it comes to its price and games lineup at launch.

I want 4D(S)

To have roughly the power of the Wii U (so a bit more than Vita) looking at mobile hardware now in a year or two it should be feasible to do for a reasonable price.

Also as others said:

Decent resolution screen
Dual analogue
Account not tied to single system
Pretty much all the things Sony got right with Vita and a shared Virtal co.sole (for cross buy of retro and eshop titles when on more than 1 system)
MMO Pokemon

Its still early to be talking about a new sucessor to the nintendo portable. It will only release around 2016 the earliest.

What i want though? Dual analog and games.