I agree with those who argue that the airlines not only have the right to devalue miles, but can be expected to do so in an environment of huge losses and gazallions of $$$ worth of liability in terms of miles on the books. Looking back to the beginning of FF programs with American Advantage, non-expiring miles are the greatest innovation ever for travelers, IMHO. It's also what has given rise to discussions like this.

Like money or stock, if you want to redeem your miles for what you consider to be today's full value, then you need to redeem TODAY. If you want to carry a large balance, then you will continue to be exposed to the liability of changes in the program until you redeem for an award at the price in effect at the time you take action. You can't have your cake and eat it, too.

My own response is to try not to carry a balance of miles in my FF account that would be greater than I would require to purchase two r/t tickets to anywhere in the world at a moment's notice without worrying about capacity controls (around 200,000 miles). Others have to decide what works for them, but the writing seems to be on the wall in terms of devaluation, doesn't it?