The majority of people who get on a plane probably don't pay FFPs much attention, but that's not the market the airlines were going after with FFPs when they were introduced.

The majority of those current frequent flyer business travellers who currently routinely use a FFP enough to earn some kind of "elite" status with the airline and/or airline alliance would probably adjust their habits if their airline of choice were the first to ditch a FFP entirely and travel decisions were actually somewhat within their discretion. I presume that, as an entire group, this is a segment the airlines have hitherto been afraid of alienating too much because of their overall net contribution to the airline exceeding their proportion of the customer base. In other words, I wouldn't be surprised if a minority (e.g., less than 25%) of some airline's customers account for the majority (e.g., greater than 50%) of the airline's revenue and for an even greater proportion of whatever could be classified as being a cash positive and or margin-improving contributing customer to the airline.