For those unfamiliar with the history of cargo flying and combi aircraft, AF/KL liked to fly Combi pax/freighter AC on many routes.
The problem that NW had was in the USA, the FAA would not certify a combi unless the Freight section was forward and the pax section was aft. Something that market research showed was not favorably received by passengers?
KLM got European certification with pax forward and freight aft on some of their 747s (-300s if my memory is correct).
Not sure if RA would be interested in another pure cargo operation, but I guess he would at least entertain some sort of combi operation that had better revenue numbers on thin routes.