But it's still a violent R rated game so it won't be accessible to the larger gaming audience so I can't see it getting more than 7m.
GTA V sold over 75m, an R rating isn't a limiter.
FW - ~2m
Lifetime - 9m
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)