QF Long Haul has around 350 less pilots flying its fleet than it had 4 years ago.
Even with that almost every pilot category is operating on min hours. There is a lot of slack to be taken up before recruitment happens. Bring on the new type.
Pure Seniority: There are only 440 captains slots at this time in long haul. There are about 40 permanent FO's so the pure seniority number required to get a LH command right now is about 480. (yes I know there are currently pilots with commands on numbers higher than that.)
I put that out there because even with a new type, some former 767 captains may not re-qualify for a LH command for a long time. The 737 may be their only option till we get a LOT of new type aircraft, remembering that the 747 is likely going to disappear in the short/medium term and the pilots will have to go somewhere.
The same situation applies for FO's, with different number thresholds of course.