Despite all these rumors and such , I'm not 100% convinced this thing is coming as soon as we've all been lead to believe.
As Eurogamer established in their article a week ago , the next big drop in semiconductor fabrication for GPU's is 14nm. CPU's just started using it this past year with intels 6000 series. Consoles rely heavily on performance per watt and heat generated per watt to make their closed off nature function reliably.
So in order to make a box that takes up as much physical space as the current PS4 but doubles the performance, you need to make the chips half as big. 14nm being half the size of the 28 nm chips found in a PS4 means this is do-able. In fact, it means 2 things - once the 14nm parts can be reliably manufactured in bulk you'll see a much smaller version of the PS4 made available that should also cost sony substantially less to manufacture which translates into probably price drops for the end consumer. Thing is , I don't think the 14nm chips can be made quite so easily , intel had problems making enough 6700k's to meet demand last year and that shortage inflated prices. Sure, that's their top end chip which required the best of the best components but still. I'm not positive on this but I think GPU's have to handle a lot more stress than a CPU does , especially with the way games are rendered internally these days. Those parts HAVE to work. So , if the regular PS4 has a 28NM custom "tahiti" GPU (7970 PC videocard) with about 25% of it's power disabled to improve yields and lower power use, it's possible that the PS4K could make use of a 14nm "Fiji" GPU (currently available as AMD's Fury) or even the new polaris line (I'm doubting this because I think it would cost too much) . Something that will be more reliably manufactured and sold more cheaply if it doesn't start getting built until 2017. Currently, the Jaguar has a succesor in the form of Puma, I imagine a custom built version could be made for a PS4K that has the same 8 cores the custom Jaguar contains while also using only 25 watts but managing 2.4 ghz + instead of 1.6 + ghz. Perhaps this is the point of contention with regards to spending more on a CPU though, as AMD is launching "summit ridge" this year which is aimed at competing with intels 6000 series CPU's. Perhaps a cheaper custom version of this is getting looked at ?
All this tech rambling aside, my point is that the big leap forward required to make a new console at all worth it can't happen cheaply (from a manufacturing standpoint) until next year so , simply put , I don't buy that PS4K is coming out until at least next fall. Waiting until say , September 2017 to launch might allow Sony to get the cost down to that 400$ USD price point that worked so well for them in 2013 , it also means this holiday season and much of next year the hardware won't be changing. People can feel safer buying a PS4 over the next 18 months in other words. As well, in the meantime , you might well get that PS4 slim available by next March. Sony needs to maintain profitable hardware but also be able to drop prices into mass market territory. As well, in order to spent the power increase even more , the regular PS4 needs to be half the cost of the PS4K by the time it launches.
Despite the second rumor about developers using all the extra juice available in the 4K devkit and regular PS4 owners having to suffer with worse graphics, I don't think you'll have a full generation leap forward here. Most games that utilize PS4K levels of power will just step down settings in the same way a PC game goes from high to medium. Sony might even have licensing fees set up so that buying a PS4K license gives you a PS4 license but you need to make the game run on both , I still don't see a point in the PS4/4K lifespan where buying a brand new game will mean you can only play it on the 4K. It will be a simple case of - do you care if your games look their best or not ? spend 200$ in a year or 2 if you don't care and spend 400$ if you do.
I just meant 3 years as an example, i feel like the problem with anything less than 5 years could be that you would get such comparatively incremental upgrades year on year its not worth it. 
