I'm surprised there seems to be so much shock around here and so many comments which are based on the original variants or outdated info?
We know the new revised consoles - Scorpio/PS4K(Neo) are meant to feature faster GPUs AND CPUs compared to the older versions; latest info suggests the specs of the GPU may well be similar to the announced RX480, which should be about GTX 980 level. Polaris/RX480 is going to cost for a 4GB consumer card, around $199. The cost for the actual chip itself will be substantially lower if you take away all the memory, PCB, distributor etc costs involved, and means realistically cost could well be under $100 for the chip itself. Now I assume the upgraded consoles will sell for a premium over the old ones, rather than necessarily replacing them; making this cost somewhat more believable. Then, eh walla, you have GTX 970/R9 290X performance in a console. Polaris is looking very much like it may bring previous enthusiast/high grade performance to a mainstream gaming price point in desktops. It could do the same in consoles.
As has already been stated, R9 280/290s/980s CAN do 4K, just not with high settings, the polaris chip may well be stronger. As it is still GCN based, there shouldn't be too many compatibility issues between titles.
Throw on top a console is FAR more optimised and focused on than a PC, as the devs and manufacturers are targetting a single spec (well two in this case), rather than thousands of subspecs with the PC, and over the life time of a console, eek far more out of the hardware than PC devs will do, as PC technology keeps moving forward.
You also have to remember that due to sitting distance from the screen, consoles can and generally do make far more shortcuts graphically to ensure framerate or overall settings are maintained. You notice on a PC because you're sitting so close to the screen, sitting 6+ feet from a TV some of the shortcuts employed are far harder to notice unless you're looking very closely, yet save some reasonable hardware performance to use towards 'the bigger picture', and still looking reasonably good.
Honestly, I think the suggestion made earlier in this thread of a few game profiles being used by Devs is very sensible, and quite possible, and would mean the Devs would not need to do too much additional work beyond a little testing and tweaking of the exact settings used for each profile; with the profile used determined by the display res/method and model of system. Not too far off what is already done!
1) Base Xbox One/PS4 - 720 60FPS/1080 30FPS varied settings
2) Base Xbox One/PS4 - VR
3) Scorpio/PS4K - 1080P 60FPS/High Settings
4) Scorpio/PS4K - 4K 30FPS/Varied Settings
5) Scorpio/PS4K - VR