Just one game will never save a console
I think Xbox one will be save with a price cut ,3rd party games and big Microsoft ip but will never win against ps4
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