It looks like that 4K version of the PS4 will arrive sooner rather than later.
Kotaku reported earlier this month that Sony has been developing a PS4 with more graphical power so that games can run at 4K resolution. It might not be an entirely new console but a new device/add-on that'll bring the much-needed power boost. Whatever it ends up being, it is currently going by the name PS4.5 and will include an updated GPU to support 4K resolution for games and more processing power for VR games.
The Wall Street Journal has now added to that report, claiming the upgraded version of Sony's console will be unveiled before PlayStation VR launches in October. The upcoming device will support 4K graphics and come with extra power to handle virtual reality experiences from the PlayStation VR. So, you can expect an updated processor and GPU, but we don't yet know when exactly it will launch nor for how much.
The new PS4 at this point seems to be a mid-cycle upgrade rather than an add-on device as first speculated. Either way, most people are losing their minds at the idea of Sony releasing an upgraded console, especially so soon after releasing the PS4. It debuted in late 2013 and is already considered to be aging/outpaced by modern gaming PCs. Many expected it would be another six years before Sony updated the console.
Although lengthy breaks between upgrades tend to be the standard when it comes to videogame-console releases, Microsoft recently talked about hardware innovations in the console space, leading some to question whether it is considering a mid-cycle upgrade for the Xbox One too.
All we know so far is that, by supporting 4K resolution (four times the pixel size of 1080p), the PS4 would be able to round out its high-res capabilities. It currently outputs 4K photos and videos, but not for games.