That is because IHVs have industry standards to abide by such as graphics APIs like Microsoft DirectX and cross licensing x86 CPU patents. The same goes for memory standards as well since the industry agrees by JEDEC standards. That is why PC's are allowed to have such different configurations ... 

Until Nintendo can agree to ONLY one or similar GPU micro-architectures that type of scalability can't be easily achieved and even if they agree on a similar GPU micro-architecture as their basis there's still quite a rift between mobile and console when it comes to the power wall ... 

Despite vita been a much newer platform the PS3 is an order of magnitude more powerful than it ...

Since handhelds will never be able to match up consoles when it comes to power consumption, Nintendo has to either hold back their home platform in terms of power to make their games playable on their handhelds or forego that idea altogether for third potential third party support ... 

You simply can't have it both ways ... 

PS4 and X1 are a MINIMUM when it comes third party game performance, not a MAXIMUM ... 

Oh I don't think there's really much question that Nintendo is going to use basically the same family of CPU/GPU (likely mobile centric) for all NX types. 

The days of a completely different home console and handheld are over, and it's impossible to support that type of a setup anyway any longer ... there's no way Nintendo would be able to make 9-12 360/PS3/Wii U ish level portable games a year combined with another 9-12 distinct PS4 level home console projects. 

That's just impossible. So really the unified platform approach is really the only way they can keep making a handheld and a seperate console SKU, doing it the old way only worked because handheld games in the past required dramatically lower resources, but today when you're getting into handheld tech that is quite high end ... no way. Can't just crap out a handheld game with a team of 12 people anymore like the GBA days and we're seeing the 3DS + Wii U as is Nintendo is basically unable to support both at the same time. 

I think Nintendo basically came to this conclusion several years ago which is where the NX project stems from. They could not continue as is, just upgraded the Wii U + 3DS lines by a generation each time and still expect to have any software ready in time to satisfy either market. 

Unless the bottom screen of the NXDS has the exact same shape, that's not happening. Not to mention how the ruins BC for the DS, 3DS, and Wii U for no good reason.

There is only so much you can do with scalability. Certain graphics settings can be scalable , however physics, AI, things like that will always need to take the weaker Handheld into consideration. If one game cart for both means intentionally gimping the Console version for the sake of cross-play, then I'd prefer it if the games were separate. If there's cross-play, then only for certain modes in a game.

If so then don't expect much 3rd party support on the NX ... 

Nintendo basically has to bear the entire brunt of supporting both platforms ... 

The unified ecosystem approach won't work for 3rd parties since Nintendo are basically declaring that their next platforms won't be competitive with the current HD twins when it comes to power ...

Exactly ... 

Geometry processing isn't all that scalable either since LOD considerations must be taken when it comes to a power constrained handheld. Micropolygons are bad enough when it comes to quad utilization. Tessellation would be a mobile platforms worst enemy when it comes to performance ... 

I think developers would prefer this. I mean it should have the userbase of the 3DS, but with at least decent amount of horsepower to go with it. 

If I'm a developer I sure a hell would prefer that over the craptastic Wii U which has 10 million owners after almost three years on market, or the 3DS which has a decent userbase but is so far behind any modern type of engine that to make games for it I'd have to make something from scratch using PS2-era assets which doesn't work for my devs or even my consumer base who expect a more modern experience for my big franchises. 

This would be kinda the silver bullet, where as a developer I can make one game basically, and just scale that up and down, and it covers the entire Nintendo "check box" for me as a publisher ... I think many devs would prefer that instead of kinda having to pick and choose between the pros/cons of the Wii U/3DS and then basically getting fed up with both and saying "fuck this, lets just support Sony and MS". 

Look at NX already ... it pretty much by virtue of DQXI (and DQX and FFXIV possibly) alone has better third party support than Wii U, lol. If they get good support from Square-Enix, they are already miles ahead of where the Wii U is at right now. 

I dont think so. They are very stupid. Anyways, they are doomed to die soon so dont worry to much.

I don't know if PS4-XB1 ports are neccessarily out of the question in a unified platform structure either.

PS4-XB1 are pretty dated tech for 2016 standards, and mobile tech is starting to catch up.

You could have a teraflop plus chip based on mobile tech in a console that has the benefit of being plugged into the wall at all times and you could have a little brother portable version of that chip for the handheld.

If it's getting Dragon Quest XI and they are looking at Final Fantasy XIV, perhaps there is more horsepower than we think.

Developers WON'T prefer this and that especially applies to western developers ...

Japanese game publishers will continue to support Nintendo's handhelds but the same probably can't be said of their console if they take this route ... 

If Nintendo does go this route then you will only see more enhanced portable versions of the said games developed for the ecosystem, not the full blown flagship AAA games like Final Fantasy XV, KH3, or other stuff that you want to see ... 

If japanese devs want to make a high end AAA console game then they will most likely ignore Nintendo's next console since it was held back in order to make the games compatible with their handheld ... 

For crying out loud, FFXV runs 900p on the PS4! If the NX only becomes marginally more powerful than the WII U due to Nintendo holding it back for their portable system then you can pretty much kiss high end 3rd party support goodbye ...