I can only comment on the changes to the FF program influencing me. My trip to Australia went to Qantas this year (an AA redemption this time but I will pay a preimum to go on the A380 next time), my family (4 fares) trip to Scotland is on Iceland Air next month (though to be fair we often took Transat before because they were the only direct option), and the trip to Hawaii at Christmas is on Delta. Because all of them were the cheapest. Before I may have paid a 10% premium (or so) to go Air Canada for the status, but it is not worth that any more. I don't know if I'm unique or not in their customer base. I suspect I must be, or the numbers would be impacted more. It was still about 8 or 9K of money going somewhere else.
My suspicion is based on conversations I've had is that people don't monitor their benefits. They do seem to notice when benefits are removed the first time they try to use them. However, that might not be relavent. Because the loyalty program participation is not as simple as people choosing one for the benefits alone (it may be the ease of accrual, like skypesos for example, or where you live) it is likely too complicated to attribute any real impact of changes to the FF program.