I don't think anyone is suggesting they would get rid of FFP. But could they raise the price, offer less days, etc? Probably. But it is pretty well known in the theme park world that AP holders in a single visit spend less money than a day visitor or a vacationing person. Reason being is if you are going 15 nights, you are buying 1 shirt, not 15 shirts. You probably have a budget and you stick to that budget each visit. A single day person probably has a larger budget for that one night than you do for your one night because you are going 15 nights. Now is there exceptions to this rule, of course. But all of the parks have looked into this and they all conclude that in a single visit AP holders spend less. I have been on your side of the argument because we spend a crap ton of money at the parks, but I had to come to the conclusion I am not normal. However, I spend very little on Merch and everybody that visits the park not as an AP spends more on merch than I did. So I have to concede that the research the parks have done is accurate.
Now does this mean all parks want to get rid of AP holders? hell no. They do want to direct AP holders to less busy times though. So if Sundays are getting crowded they may reduce the number of Sundays on the passes. Or raise the price to price out the lower budget people that spend the least amount at the parks. It is the reason the Uni CA and DL restructured and changed their AP holders. They needed to reduce the number of people on crowded days, so they wanted to reduce AP holders. It is also why WDW changed their structure and essentially added black out dates to their annual pass. They decided to give us Photopass because probably 90% of AP holders never bought pictures anyways. So they are gaining more by getting us to not come those 4 busiest weeks by giving us something we never spent money on anyways. It was a huge win for them and not a PR disaster to AP holders.
Uni does these types of surveys all the time for their regular AP holders and HHN people. Mainly because they want to see where that tipping point is. How far can they go without harming their bottom line, but accomplishing what they want to accomplish.