How does Paizo's "player acquisition and customer churn model" function, in comparison to TSR/WotC?
D&D is a gateway game; Pathfinder is not (and is not marketed as one right now, either - though the Pathfinder Society is at least trying to keep the doors open to new gamers with organized play). People who start with RPGs are overwhelmingly likely to start with D&D more than any other system. (V:TM might have once been an exception to this when it came to female gamers, however, WoD's popularity has decreased a lot over the years - I don't know whether this is still true).
Whatever the case, people start with D&D and the overwhelming number of those players "churn out" of gaming and leave the hobby within three years or less. Those that do not churn out, stick with it and remain casual or lifestyle gamers and play D&D until they eventually churn out and leave the hobby many years later -- or graduate to another game system. Pathfinder is one of those "graduate to" systems. Right now, it's the most popular, actually.
So those are the kind of people who are most likely to play Pathfinder. There are a lot less of them than "ordinary" new gamers, but they tend not to leave the hobby for quite a while.
Which means that Pathfinder's players, like those gamers who play all "graduate" or second tier games will tend to be gamers in for the long haul within the hobby. They are less likely to leave the hobby and stop being your customers, as a relative percentage to D&D's customer base - the large majority of which
do "churn out" of the hobby.
Does not mean Pathfinder's customer base won't leave the game for another RPG within the hobby, mind you. The biggest risk would be losing them back to D&D with that game's 5th or 6th Ed. For the precedent in FPRG gaming, look to GURPS and Rolemaster, which were both the big second tier FRPGs of the late 80s and throughout the 90s. The large majority of the customers of those game systems "came back" to D&D with 3.xx.