I roughly calculated about 20 additional airframes after the B734's have been replaced. But by the time the last of the order is coming through, Jetconnects aircraft will be even older. I can see them being replaced by the earlier QF 738's, roughly 10 or so.
It will still be an increase to mainline, but I think only by about 10 or so. I like to see mainline increasing also, but it looks like Jetstar will have almost the same amount of aircraft the way it is going.