I've always thought that VLAs made sense for QF - whether 747 or A380. There are a stack of high volume, long haul routes where, because of time zone shifts and distance, only a few windows make sense for the business market (LAX, DFW, LHR etc). No point running two or three smaller planes, when you can fill a single larger plane.
Obviously, the 787 and Sunrise, if it happens, starts to break down that logic a bit.