My fear is that if they go for PS4 performance, they'll price them out of the one market they're good at controlling - the youth market.
I'd rather that they have three systems early on:
NX Console (PS4 Level) $300/350
NX Handy (Vita Level) $175
NX Mini (NX Handy as a home console w/HDMI and the same controller as the home console) $125
I just think that having a presence there is really important.
Nintendo is still likely to surprise us with an interesting controller though.
Honestly, I think that, in the beginning they should go for this:
NX Home: $299, optical drive/cartridge slot, HDD (500 GB), one standard controller
NX Portable: $199 (ideally, $149 but I don't think that's happening)
NX Mothership (Yeah, I know, way too cool a name for Nintendo): $449, includes both Home, Portable and download code for a game (could be an indie game, doesn't have to be AAA title)
Also, expecting NXP to be at Vita level is a bit too pessimistic. Vita has ~50 GFLOPS. "Crappy" Adreno 330 (Snapdragon 801) would give you 3x that (158 GFLOPS) and top of the line, Adreno 430 would give you 388 GFLOPS. There are of course monsters like PowerVR GT7900 which goes up to 819 GFLOPS and Tegra X1 that will be capable of ~1 TFLOPS. Of course, Nintendo probably (surely) won't go for PowerVR or X1, but I expect at least 400 GLOPS GPU in NXP, if "industry leading chips" rumor is true. Also, since Nintendo is most likely going for off the shelf parts, there is bound to be some heavy customization in the works which are bound to provide extra performance
Regarding NX Home's power, I don't think they necessarily need to aim for PS4 performance. Providing performance similar to Xbox One is enough, IMO, and that shouldn't be a problem in 2016. Reaching even PS4 performance shouldn't be a problem, however, I'm taking into account that Nintendo will make some cuts in order to maximize profits per unit sold.
Biggest struggle I see Nintendo having is getting western 3rd party developers on board. Decent specs might be enough to generate initial interest, but console sales will decide if the big 3 (EA, Ubisoft, Activision) want to stick around for a longer time. In the end, it's all going to depend on how low Nintendo is willing to go with NX's price. Ideally, they would price the console at $249 and handheld at $149, but that would probably generate loss on the hardware. However, those price would insure a very strong market penetration and that is precisely what Nintendo needs after WiiU's abysmal sales.
They can keep the kid audience on handhelds.
I'm 31 and N3DS is my primary gaming device (bought PS4 at launch but I sold it). I prefer gaming devices with dedicated screens since I don't want to compete for a single TV in my apartment (I'm married and have a kid). And before you say that I can also play on my phone, I tried that, but lack of buttons and lack of meaningful gaming experiences on Android/iOS killed smartphone/iPad gaming for me.
So, if your perception is that "3DS is for kids", you are perceiving only a part of 3DS' market.
The system is likely to come out at the end of 2017 though.
Are you saying that Nintendo plans to ride that massively successful WiiU tsunami all the way to the 2017? No. Just no. Console will come out Q3/Q4 2016. at the latest.