The only way for all of the airlines to do away with their programs would be through illegal collusion.

There would just be too much incentive--either from the perspective of "soft" business calculations or more quantitative economic game theory considerations--for an airline to be the only one with a program.

That being said, I do believe that there is a real danger of the various programs beginning to administer spiraling rounds of benefit dilutions to see how much they can get away with--up to the point where their customers make it very clear to them that these actions have become counterproductive. This is why Delta elites must make clear to Delta management the negative consequences to them of the recent changes in your program--and nip this nonsense in the bud!