GT sport is basically a glorified GT7 prologue. With that in mind I think it will sell 5m+ and will be very financially success for what it is.
How much over 5m? Who knows because ps4 is a behemoth so it could be really big. But I think 5m should be the goal.
GT7 can go for the 10m+ target. 7.5m retail and 2.5m digital.