But there is the interesting thought that because there is a 1:1 ratio for dollars spent to miles earned (at a minimum), inflation itself dictates that going forward an increasing percentage of total miles earned will come from credit cards, and not flying. The distance between two given cities doesn't change! Thus, this inflation in miles earned relative to flying does seem to indicate that award availability will go down unless airlines stop accepting so much cash from their passengers and decide to allocate more seats to FF redemptions. This seems unlikely in the near term given that in the current environment the airlines are getting away with having their cake (in the form of increased dollars from Amex, VISA/MC partners, etc) and eating it too (still allocate the same % of seats to FF redemptions) ... redemption difficulty will continue to increase going forward!

Long term solution: Airlines can allocate more seats to redemptions or increase the price paid by Amex etc to buy the miles for their customers (implicitly causing them to cut back on miles given out or break the 1:1 ratio). . . or just push it as far as possible until the programs implode in customer dissatisfaction, legislation or class action lawsuits. Ultimately, raising the award redemption price doesn't work because people who pay to fly would never be able to get a decent level of miles for a reward (again, going back to that little fixed distance between cities issue). Hmm...