Originally Posted by
Boghopper
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.
Ok, let's imagine that the frequent flyer programs remain basically unchanged for 100 years. A 2500 mile flight will remain 10% of a domestic FF ticket (on most airlines), and inflation is irrelevant. However, each mile will become more valuable by the inflation rate. The airlines will have to charge the credit card companies more for each mile. Whenever they actually do that, I would expect the credit card companies to "devalue" and offer less miles per dollar spent by whatever factor their cost increases.