Never going to handle.

Sony aren't going back to the handheld market, and they are especially not going to release an underpowered console just to to make it hybrid.

I would love to have portable PS4. Most of my gaming has been done on portable systems (right now Switch, before that it was 3DS + Vita), because I love the convenience and realistically I only have enough time to game on portables. With that being said, I don't think the PS4's architecture would really scale down well into something portable, not even in the future as process nodes shrink (look at Switch, it is using a completely different architecture as opposed to taking what was in the Xbox 360 and PS3 and trying to shrink it). However, we could see new SOC architectures in the future that are designed for mobility but are as powerful as a base PS4 (in fact, it is mostly a matter of "when" as opposed to an "if"; the Switch in handheld mode is about as powerful as PS3 and Xbox 360 and its SOC came out about 10 years after those systems were released).

Thus, the problem here is not the hardware getting there but rather it has to do with the software. Having a portable system that is on par with a PS4 but not based on the PS4's architecture means that it would likely not be software compatible with it. Thus, the system would need to build a large enough base and/or Sony would need to make the porting process so convenient (not to mention bring first-party PS4 games themselves) that devs would be convinced to port their games over.

Apparently very few can see Raven Ridge, and even some who do refuse to acknowledge its exsistance. I was very shocked that Mr. Leadbetter did not bring up this possability, and even more so when he claimed AMD lacks the core technology to make it happen. 

I still think Sony and AMD could take what has been learned over the last 6+ years, and significantly reduce the power consumption on a 7nm revision to the current PS4 APU. They have plenty of Memory choices that they could make to meet the needs of a PS4 at much lower energy draw. This would likely be the harder road, and may not pay off as much in the end, depending on where they are taking PS4, and when PS5 is coming out.

So, what is the other option? Exactly what you are talking about. Make a custom 7nm Ryzen Gen 2/Navi based chip, use either GDDR6 or HBM2. Now you have a device that blows the PS4 out of the water in the CPU department, and should be able to best it in the GPU department by quite a bit, all while falling in that ~10 watt teritory.

Now in theory, Sony should be making PS5 backwards compatible with PS4. If they are doing this and PS5 uses a Ryzen Gen 2/Navi based chipset, then they would already be working on making Ryzen Gen 2/Navi capable of running PS4 code without any modifications needed. Taking things even further, if they went this direction, then the PS Mobile device, should be ready to run PS5 titles at lower res/ lower frame rate, in very much the same way PS4 and PS4 Pro works right now. Effectively making it more of a PS5 Portable. 

That is what I see looking off into the Road maps, and what technologies will be available by the end of 2019. Will Sony or Microsoft take a stab at it? Probably not, but I really hope they do. I think the market would go absolutely crazy at the idea of having Call of Duty, Battlefield, Grand Theft Auto, Assasin's Creed, Gran Turismo, Uncharted, The Last of Us, Halo, Gears, and Fozra/Horion all available on the go, with no compromise. But, that's just my thought's. At any rate, I look forward to what 7nm fabrication brings us, and where things go with Sony and Microsoft, whether it is Home, Mobile, both, or otherwise. It's all about gaming first hardware, and that is what I love.

The question is will Sony's first party accept it?, they can surely produce it but teams like ND, likes to work on much more graphic capable system, I doubt that

The first price cut in both Japan and US coincided with each other, so it is odd nothing happened in Japan with regards to the price in Japan with the launch of the Slim. 

Although the strangest thing by far in Japan is why retailers are selling PS4 below RRP when the system is currently supply constrained. Typically, retailers sell above RRP when demand is higher than supply. My only guess is that the retailers are competing with each other for orders.

I've given up on portable. I hope SONY has learned it's lesson and continues to do so too.

sony should go their own way

Like DF stated, PS4 for 720p games could be possible in few years but form factor of such device would be similar to laptop, and than every single game would need a quite of rework to run at 720p and at weaker hardware (definitely some 3rd parties wouldn't want to do that), so all that dont sounds attractive at all so hardly that Sony would try do something like that.

Reread what was said. You made a falsifiable statement " The NS is too weak to play current gen playstation/xbox games "

I provided two examples which falsified your statement. 

If what you said isn't what you meant, then be more precise with what you actually say next time. 

"sony fans don"'t want that" tell that to the large amount of Vita buyers and Vita supporting devs in Japan.