If they will do a price cut it will be at Gamescom not E3 ,Sony could see how much xbox one price cut will help it and if they feel like xbox one with star selling better then PS4 constantly they will do a small price cut
PS4 - over 100 millions let's say 120m
Xbox One - 70m
Wii U - 25m
Vita - 15m if it will not get Final Fantasy Kingdoms Heart and Monster Hunter 20m otherwise
3DS - 80m