I think anybody who sees an "end" to FF programs is being myopic. Rewards programs across the consumer spectrum are expanding in number, not contracting. Pretty much every retail outlet now has a rewards currency, even if that's a punch card for your 10th smoothie for free. FF programs are just rewards programs on a massive scale and,even ignoring the facts of their profitability, there's no reason to think they would go away.

What is happening is the values for customers (and thus liabilities for airlines) are being reined in. So outsized premium cabin rewards are disappearing, miles are harder to earn BIS-wise, and "dynamic pricing" is sealing redemptions within controllable ranges. Additionally, free upgrades are disappearing and being replaced by last minute buy-ups. Much of the value of the programs is being swiftly eroded in the US and Europe; I am no Asian airlines expert, but it seems a slower process with the major players on that side of the planet. But cutting value doesn't mean the programs will disappear. Once the programs reach a certain "lack of value" threshold they will be upgraded or replaced by better ones that do what they are supposed to: drive incremental revenue. But they won't end as a whole.

To use the GreenStamps example: yes Green Stamps eventually destroyed itself as the economics of the industry and the company's particular financial situation declined. But what you're missing is that grocery loyalty programs have EXPLODED over the past 20 years. Every single grocery chain has a lucrative points currency now, while Green Stamps are dead. Forecasting an entire industry's decline by the example of a single player's collapse doesn't match reality. Programs are replaced by better ones, and the world moves on.