Even though it's not even confirmed, someone as already tested out the new PS4 Slim and posted their review on youtube
Through the video, the reviewer claimed that he doesn't own the PS4 and that he doesn't have it anymore which makes wonder where did he got it in the first place although it looks very authentic since they did an unboxing of the gaming system.
Unlike the new Xbox One S, the PS4 Slim doesn't support HDR and it can't upscale games into 4K or it supports the new 4K Blurays which makes us believe that all this features will be on the new PS4 Neo that's rumored to be announced pretty soon.
There's a bunch of changes into the PS4 itself with it being smaller and having the front USB ports a bit spread out, no optic entrance and with the new controller also a bit different with a light panel on the touch-pad, a better D-Pad and with better response into the games if the controller is connected by cable.
If you want to know more go ahead and check out the review