I admit to being far less savy than many on here and perhaps even ignorant to the real economics of an airline loyaly program but it seems that even under the current difficult redemption scheme for int'l biz flights that Delta does derive some benefit from filling a seat that wouls likely have otherwise been empty or filled by an employee with a "paying" passenger. Some revenue can be booked from the miles used (i think) and you've presumably made a loyal customer happy. If DL converts to a dollar based redemtpion strategy whereby the current 200k int'l biz seat become based on fare and increases by double, then wouldn't more seats just sit empty since there are probably few members with 400k plus miles to use? it would seem difficult to book revenue for an empty seat, even under the most creative of accounting. When I fly to Dulblin for instance, and I do so a few times a year, both DL and United's (CO's) Biz class are filled with employees or mileage travellers (anecdotal on the latter through conversations). I suppose this could be a bonanza for employee travel...
this would also seem to evisorate the AMEX tie-in. Membership Rewards points for instance would be far more valuable elsewhere unless massive promotions are employed to compel folks to xfer to Delta.
just some random thoughts..