Will be interesting to see how Rise performs compared to World on PC, would assume Rise will sell less.
Monster Hunter World sales were actually leaked in the major Capcom hack at the end of 2020.
PS4 - 8.90m
Assuming similar splits (which is most likely accurate), PS4 should be at 9.25M now.
MHW reaching 18.7M results in PS4 being 10M, which should happen.
Since Iceborne requires World,
PS4 had 61% of Iceborne sales, LTD is at 8.2M -> 5M on PS4/5
Total MHW sales on PS4/5 = 14.25M