Well, if the PS4 is only supposed to drop by 2M in this FY, then Sony has to do something to slow it down, and slow it down a lot I think. Because at the current rate, 14M would be a much more realistic target.
The thing is though, those calculations don't and can't take a possible PS5/neXtbox reveal into consideration. Even if a super slim is announced and one SAD released, PS5 and neXtbox may well negate it.
Please remember... They are 6 years old.