Lets not kid ourselves here. Whilst its entirely possible that this thing can output 1080p at 120fps you need to remember the graphical hit that is gonna take place in order to get there. Your going to be talking seriously scaled back effects and textures to hit those frame rates so anyone expecting to play normal quality PS4 titles is going to be disappointed. Your more likely to be looking at upscaled PS3 quality visuals in order to achieve this.
PREDICTIONS FOR END OF 2015: (Made Jan 1st 2015)
PS4 - 34M - XB1 - 21m - WII U -12M