But none of this addresses the relationship between the two earnings methods. Imagine 100 years from now, inflation will have increased prices in nominal terms by multiple times. Imagine that CC holders are earning eight times the current number of miles on their purchases and all the destinations are the same distance apart. Does this matter to the airlines, or are they content to let their mileage programs become credit card reward programs with actual miles flown adding what amounts to a rounding error. Or maybe in 100 years the planet will be so hot we'll all be running around in loin cloths and scrounging for invertebrates to ear.