I take a different point of view.
It seems to me that airline prices are about as cheap now as they have ever been. So it is not unreasonable to me that airline prices are as cheap as they ever will be. Therefore I have been saving my miles and am buying tickets.
Sure the airlines might devalue the miles. But it seems more likely to me that they won't devalue the miles and they'll increase the price of tickets. In that case, miles are a great hedge on inflation.