Apparently Nintendo's heading toward an Apple/Android-like approach; where there are multiple devices with a similar architecture/OS, making porting of games and assets very easy and streamlined between the systems. This specifically to up their software output and avoid game droughts.

Iwata has said all this on several occasions. So we can reasonably expect Wii U and 3DS' successor and also Wii U's successor to share the same OS, architecture, and games (or very similar ones, at any rate). Also, there may be more updates/redesigns in the future, like how Apple's bringing out new iPhones and iPads every year.

http://www.vg247.com/2014/02/04/iwata-discusses-next-system-promises-flat-ios-like-architecture-across-handheld-console/

The net result will be the same. Only Nintendo fans will buy a Nintendo "PS4" over the actual PS4. I don't think third parties will even give them token support this time around either, Nintendo will have to pay the piper for the Wii U flop and that means little/no trust from third parties. They will stick with PS4/X1. 

PS4 will be $299.99 by fall 2016, X1 may be cheaper, both will have hundreds of games and developers will have all their resources invested there. PS4 will probably be sitting at around 40 million userbase headstart, that's even larger than the headstart the PS2 got over the GameCube. Nintendo wouldn't even be competetive. If you're talking 2017, the situation will be even worse, PS4 will probably be $250 and the userbase will be past 60+ million, while Nintendo is starting at 0. 

Nintendo will need to either release something much more powerful than the PS4 (which I doubt is in the cards) or something that's a budget device, I think that's probably more likely. Something that allows people to play handheld games (from Nintendo's next-gen handheld) on the TV as a side option, like the Vita TV is far (far) more likely. 

You are right in same point, but same users will have the PS4/Xbox One for 3+ years and maybe will want new console.

Give a third parties hardware they want like PS4 and they will make games, because they can make ports with similar hardware without losing 2 much time and money.

Next Nintendo console will probably not have price above PS4 price and hardware probably will be little stronger than PS4.

If Wii U was launched in 2010. and not 2012, Wii U would be in better position, and next Nintendo console will not have big Wii U problems.

I think they are quite happy with Wii U level graphics, that's probably taxing their dev teams and pushing dev budgets to about the top tier that Nintendo feels comfortable with. The next handheld will be capable of Wii U level graphics just at a 540p resolution IMO, well the home TV mini-box will give you the same graphics at 1080p. And they'll be able to sell it for very, very cheap. 

So I think we're looking at a graphics jump in effect similar to the GameCube to Wii jump (not a big one). Iwata's comments about "absorbing the Wii U" I think hints at this ... they won't re-use the same chipset, but they will make a new chipset that allows for Wii U engines to have a streamlined process is being ported over and can handle those engines even in a portable (sub 5 watt power consumption) setting. 

There's nothing "new" about a console that isn't (really) any more powerful than the existing consoles that are 3 years old already.

That's the problem there, Nintendo fans will get excited about it, but no one else will. Were you impressed by the Playstation Move? Probably not, because you had already had that experience 3 years prior with the Wiimote. 

If they are going that route then it has to be built to compete with the Playstation FIVE (5) which will be out probably by 2018. 

In my opinion though Nintendo doesn't have any interest in this approach period. 

I think they are quite happy with Wii U level graphics, that's probably taxing their dev teams and pushing dev budgets to about the top tier that Nintendo feels comfortable with. The next handheld will be capable of Wii U level graphics just at a 540p resolution IMO, well the home TV mini-box will give you the same graphics at 1080p. And they'll be able to sell it for very, very cheap. 

So I think we're looking at a graphics jump in effect similar to the GameCube to Wii jump (not a big one). Iwata's comments about "absorbing the Wii U" I think hints at this ... they won't re-use the same chipset, but they will make a new chipset that allows for Wii U engines to have a streamlined process is being ported over and can handle those engines even in a portable (sub 5 watt power consumption) setting. 

The way I see it there are 3 options for Nintendo

1. Make an uber powerful machine to compete with PS5/Xbox4, 2 years before the competition. The next PS/Xbox will likely come in 2019/2020 so Nintendo will need to release in 2017/2018. At that point PS4/X1 will be $250 or less while Nintendo's new console will be $400 or more. Also 3rd parties wont all jump ship and start making exclusives for it so what were looking at is better versions of PS4 games. Will the millions upon millions of PS4/X1 owners buy a $400 Nintendo console to play games they already have access to? Probably not. Will people who dont have a PS4/X1 yet choose a $400 console over the $250 one? Probably not. So by the time PS5/Xbox4 release, 3rd parties will likely already have stopped giving this new console support which will just make it an expensive console to play Nintendo games just like Wii U.

2. Nintendo releases a console comparable to PS4 middway thru the generation. Nintendo releases this console in 2016/2017 with specs and price to match PS4 so probably around $250-300. Once again this Nintendo device will be an attempt to lure in 3rd parties so once again we will just be looking at PS4/X1 multiplats which will have large install bases and hundreds of games to choose already. People who just bought PS4/X1 recently wont move over to Nintendo and new console owners will the choose the ones with a ton of games and people to play online with. Even if these multiplats do sell decently they will probably lose 3rd party support 1-2 years after PS5/X1 release since it will be so underpowered compared to them just like Wii U.

3. Go With a strategy that is best for themselves and there loyal fanbase. Without a gimmick to lure in casuals or a near monopoly on 3rd parties, Nintendo consoles sell between 15-30 as seen by N64, GC and now Wii. So what they need to do is find a way to make a profit even if the console does sell in that range. The best way to do this is by unifying the handheld and console. 2 devices with same architecture/OS/specs/games with the console version being more powerful to play the games at a higher resolution. Handheld slightly more powerful than Vita, console slightly more powerful than Wii U which can both be sold for $199 by 2016. This will allow Nintendo to essentaily focus all developement on one platform resulting in a greater release schedule and since Nintendo handhelds always have strong Japanese 3rd party support this means the new console will as well, add to that family friendly western 3rd party games Nintendo gets plus an improved Virtual Console and strong indie support. Lets say the handheld sells 55-70 million and the console 15-30 million so in total 70-100 million which if done right will provide a strong profit.