There might well be some competition for the Boeing 747-400ERF from the proposed 747-400 pax to freighter conversion by Cargo Conversions LLC due in around two years. They are using the same door and most of the same engineering as for the 747-200 pax to freighter conversion and are not going to be removing the upper deck beams after discussions with operators. With the recent reduction in values of the earliest 747-400's I imagine this is becoming more viable every day.