I think it's likely to just be a PS4 slim with 4K output for Netflix and Blu-ray and perhaps a beefier CPU/GPU to allow for smoother gameplay and UI, PSN use:

So what do we know about the rumoured PlayStation 4.5? In the wake of last week's post-GDC outing of the hardware by Kotaku, we have independently established that it's real and that Sony's R&D labs have prototype devices, and we also have more than one source referring to it as PlayStation 4K, the name we'll be using for now. And this is where things become slightly strange - because while more GPU power is being offered to developers, realistically it is nowhere near enough to provide native 4K gaming at the same quality level as current 1080p titles. The full extent of the spec is a current focus of enquiry for us, but realistically, it is simply impossible to cram the equivalent of today's top-end PC graphics hardware into a console-sized, mass-market box.

Everything we've heard positions PlayStation 4K as a machine capable of playing current and next-generation ultra HD media, while also offering support for other aspects of the 4K spec, such as high-dynamic range and a wider colour gamut - aspects of the 4K spec that could be introduced to gaming. However, in terms of additional computational power, we've got be realistic about what Sony can deliver with a mid-generation refresh.

We can say that with some degree of certainty because PlayStation 4K will almost certainly use an evolved version of the APU technology used in the current console. Once again we will see semi-custom versions of AMD's CPU and GPU technology integrated into a single, console-friendly processor, and thanks to the firm's openness with its technology roadmaps, we have a good idea of the base building blocks Sony has access to in building its next PlayStation.

We also know about the fabrication technologies available. PlayStation 4 and Xbox One arrived when 28nm microprocessors were firmly established, and right now the industry is moving on to 14nm and 16nm chips using 3D 'FinFET' transistors. Shrinking transistors and innovative new architecture are what make generational leaps in computational power possible.

http://www.eurogamer.net/articles/digitalfoundry-2016-in-theory-playstation-4k-is-real-but-why-is-sony-making-it

It gets tiring seeing people draw straight comparisons from PC hardware to console hardware. The architecture is the same, the design philosophy, efficiency, and optimization is not.

With that being said, I'm confident that Sony can achieve 4K gaming on a smaller budget than any PC enthusiast can. The major concern for me, which is mentioned in the article has to do with the case - I think that the Ps4 was designed too small for what it is. How they plan on making this ps4k without introducing a bigger model is beyond me, unless we're about to see a next generation APU.

I just think it's a slightly beefier system that can output at 4K but don't think it's something we'll see in games. For me, Sony will want to keep the jump advantageous but not too big that it alienates older adapters. Essentially a PS4 slim. This gives them a better system to sell without negating the need for a PS5. That seems about the right ballance to me. 1080p/60fps but not 4k/30fps. Most people will be happy with that because the majority of people still only have a 1080p TV. I think I read somewhere that 4K adaption rate is around 7% in the US.

So in other words, they're speculating and don't really know anything.

Hoping a new HW with 60 FPS in games, although that piss off the existing install base.

This.

Noo.

If PS4K is real the only thing I can imagine is that they weren't able to shrink the APU. GCN 1.0-1.2 is only produced in the 28nm process by AMD and if attempts to shrink it down to 14/16 or atleast 20nm were unsuccessful (waay too low yields/many leakage problems) that means Sony wouldn't be able to lower the production costs.

To get around this problem they might have decided to go with a Zen/Polaris APU (architectures already designed for 14/16nm). But that's pure speculation.

Mr.Nintendo it is.... :3

http://gamrconnect.vgchartz.com/thread.php?id=209455&page=1#60

which is a bit of a weird way to go, as Nintendo has done this several times with their handhelds (DS > DSi, 3DS > N3DS).. I guess you are only interested in home consoles and trust them to never do that in their home console division and afaik they haven't