DM235 on 23 December 2015
Just like the PS3 slim added Dolby TrueHD and DTS-HD Master Audio bitstreaming, I totally expect the PS4 slim to add 4K video output (by upgrading the HDMI port to the 2.0 spec). I don't think you can upgrade the HDMI port on the existing PS4 models.
This is a "minor" technical upgrade, and it will not affect gaming (mainly because the GPU in the PS4 isn't powerful enough to take advantage of 4K).
Just like other generations, the PS4 slim should launch in the 3rd year of the generation (so that would mean a fall 2016 launch).
