Slighty off topic, but the Thai PER-BKK flight is at 90% + load factor most flights. So it seems it is most likely a nice little earner for Thai.
I find it ironic that a lot of the flights QF says are unprofitable (supposedly) other airlines seem to be operating on those routes with near capacity on most flights.
These airlines don't use B747's as the backbone of their fleet either, they have a mix of B777 or A330 and use them on the routes they were designed for. So PER-BKK is most likely unprofitable if you only use a B744 on it, but an A330 is mostly making money.