Don't forget, there's plenty of A320/A330 endorsed guys in Qantas. If the MOU affords them enough seniority for a command I'm sure a few guys would be interested.
I don't think you'll see many junior S/Os going across as A320 F/Os forking out for an endorsement and taking a paycut. If they had wanted to join Jetstar instead of Qantas during the past few years they probably would have done so.