I also don't think this route is going anywhere. I think GSK fills the premium cabin(s) and will not be surprised to see it switch back to 777 at some point. I also remember reading on a.net that AA also has a significant amount of cargo on this route (not sure if it's true as I've never been on the route). I was scheduled to take this route last summer on a Y award ticket, but was able to switch to DFW-LHR as availability opened up.