I realise this will be a small percentage of users, but how about multi monitor / surround gaming or what about 3d? (I dont believe Sony discounted the latter did they?)
Yes its been around for ages (on the pc), and yes currently you probably dont even need "double" the amount of vram/gddr as a single monitor user but between this and /or 3d would account for abit more on both sides (Im guessing with both of these, more cpu/apu memory would also be required?)
What about some apu based scaling for those with hi-res monitors (no not 4k lol as I know Sony did discount this on the gaming side) - but 2560*1600 shouldnt be too intensive depending on how they want to do it.
Obviously it would be ideal for devs to put this in as a "default", but if Sony want to make the PS4 as adaptable as possible without putting (more) pressure on devs.