Don't know about Joe's claims, although he may have a point, since Delta's change may just be the first step in a growing series of devaluations of miles.
But, IMHO, it does look as though, in the long run, miles are going to be worth a lot less, on any carrier. The best rule of miles appears to "burn, baby, burn." @:-) And, maybe it is time to search for a new, cash rebate card. No one can devalue the dollar!