They have only had the 346 about 1 or 2 years ???
The oldest is barely 15 months old, two arrived in September last year, one at the end of November and the fourth last march.
They are all more capable A340-600Xs too, for which Qatar was actually the launch customer.
Going back to 2004/2005 and looking over various bits of
PR when the aircraft was entering it's final assembly and early flight test, it's increased range, now higher than the 77W, it's increased MTOW, also now higher than the 77W, and its almost identical payload capability to the 77W, was pinned as being enough to turn the tide of orders that the standard aircraft was losing, or at least keep the current customers coming back for more.