small44 on 16 February 2015
Xb1 is not massively up yoy so i don't see how xbox1 has effect on ps4 this year.
It's true some people use Netflix, Amazon instant video on their console but it's not the main reason why people buy a console.
Ps4 can be down yoy but not because of the reason you mentionned
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
Essay Pro