imagine if Sony releases a PlayStation 4K model which can play your PS4 games in either 1080p 60fps or in 4K 30fps.

It will cost 700$ to be realistic here. All current exclusive will be upated to run with the better performance like Bloodborne or Driveclub and future third party games would adapt it or allready patch their current games. But it would only support higher frame rate and resolutions but not graphics.

So it would be

400$ for PS4

700$ for PS4K

so everyone has the choice

No.

Developers can barely complete their games now. How many developers are in a position to take advantage of that "Power"? Can SONY even afford that?

No! For starters it'll be more in the range of 1500$ (4k is more expensive then you think). Also developers aren't going to develop for 2 platforms that are the same except for hardware. So no, bad idea. Also very few would buy it. It would cost similar to a PC, and in that case I'd just build a PC.

At most it'd display in 4k, not render. So definitely no.

well they just have to make it 60fps or 4k not better looking 

I could see this happening later in the generation, as a means to extend it. Like in five years or something.

No because by then PC would have 4k under wraps and will be more stable with gains, I'd rather a cheaper 4k 60fps option and PC will be that choice.

well, no

Sounds like a perfect way to bungle up their lead and burn all good will built up. As an undercover One supporter, I would be in favor of this.

Then what is the point?