In idle moments I've been wondering about an inherent tension in the UA MP program (and many others). The mileage distance between any two points is fixed, and therefore there won't be any change in that over time. Inflation, on the other hand, makes everything more expensive over time and therefore there will be more and more miles earned from identical purchases. The effect is subtle, but can result in multiples over decades. If left alone, it seems to me that the credit card mileage programs would eventually swamp everything else, including miles earned for flying. So surely the airlines are looking at how they are going to adjust this, unless miles earned for flights become an afterthought (although their importance for elite status will remain).

It seems some airlines like Air New Zealand have anticipated this issue by going to points rather than miles. Will all the others have to follow suit? Or will the reduce the miles earned for spending on CCs? Or, perhaps more likely than that, they will award more than one "mile" for each mile flown and adjust things by increasing the redemption requirements. That, on the other hand, would instantly devalue existing mileage balances, which surely would cause some consternation. But if it's gradual perhaps nobody will notice (the old frog in boiling water analogy).

Thoughts?