I'd say net gain for mainline = 6 x 738s.
I believe there's 19 734s left flying with mainline, which would be replaced, plus the 5 or 6 over at JetConnect which leaves a net gain for mainline of about 6 a/c. Surely they'll firm up some options before 2017... Right? Right?
Of the 68 for Jetstar there could well be more bound for Singapore not just the new operation in Vietnam. Either way, sounds like there'll be substantial growth for Jetstar.
Funny this, I just posted a question this morning asking when QF were going to order more narrowbodies!