If it goes multiplatform! We already know it is coming to PS4/PS4 Pro "first" but we don't know if that means it will release on Xbox One and PC as well.
I could see Crash Trilogy selling over 20 million copies. It is not full priced and it appears to be a great game from a much anticipated remake of 3 classic games! 20 million is not unthinkable when we see Kinect Adventures and Mario Kart doing those numbers at higher prices.
10 million on PS4
5 million on Xbox One
2 million on Switch
3 millon on PC
At least!