For comparison this is what other PlayStation consoles shipped after the successor launched:
PS1 - ~29m
PS2 - ~48m
PS3 - 7m
So while the likely 38m it would need to ship after PS5 launches isn't unheard of, I really don't think it can do it. I'll be pleasantly surprised if it manages half of that post-ps5.
A lot of it does depend on the strategy Sony go for I guess.
Yeah, the PS1 and PS2 had legs due to late launches in a significant amount of countries. PS3 didn't have late launches and neither will the PS4. Sony is also going for profit and until they change my mind with price cuts, I don't think they will surpass 115m-125m sales.