My interpretation of this, which I drew clear back when Stuart and Euan were writing this, was that KSA would rapidly fall from producing 9.6 mbpd to around 5 or 5.5 mbpd and then stabilize there for several decades (assuming no other outside factors come into play). The logistic curves strongly support that perspective. This is how I like to see the logistic used - as a tool in conjunction with multiple other analyses that all come to similar conclusions.

"The greatest shortcoming of the human race is our inability to understand the exponential function." -- Dr. Albert Bartlett
Into the Grey Zone