How this now console would be marketed and what it means for the existing PS4 ecosystem is a bit of a mystery. To deliver 4K gaming the device would need a considerable hardware upgrade and that doesn't seem feasible at console-level pricing because you need a beefy gaming rig with a lot of graphical horsepower to play games at 30fps with high image quality settings.
We don’t know whether current PS4 owners will be able to upgrade or if they’ll have to buy an entirely new device to benefit from this power boost, but from what we hear, Sony has started briefing developers.There's no firm word about a potential launch date but the article suggests the PS4.5 isn't in the cards for 2016.
Based on conversations with developers who have spoken with Sony, this ‘PS4.5’ will include an upgraded GPU both to support high-end 4K resolution for games and add more processing power that can enhance the games supported by PlayStation VR, the headset Sony will launch this fall. It’s unclear if ‘PS4.5’ is an official name or just a nickname that developers have been using. One developer jokingly called it the ‘PS4K’ while telling me about the device.