Mainline crew might crew the B787, but you will have no choice but to do it on Jetstar T&Cs.
Ask yourself the all important question!
Q. If you were running the business(ie if it was YOUR business), why would you pay one lot of employees more than the other to do exactly the same job?
A. You wouldn't!
You blokes are dreaming if you think you will crew it under your present conditions.
It aint eva going to happen!