The ITA is showing $600/$700 DFW-HKG-DFW, scattered dates for the next few months.
http://www.gcmap.com/mapui?P=DFW-HKG-DFW That would be about right, especially if you start or end in BNA, and do the Avios booking just one way. Long long haul, but the MCE is doable on the 777-300, and you get to go to The Wing!