Why would they bother? This was suggested back in 2003 immediately after JQ launched. The logic was identical back then- a 'Jetstar class' in the last 15-20 rows of a (say) 767 that wouldn't get any food/ drinks and would have to purchase everything. It was pitched domestically but the same logic applied.
Heck, they could do that now by buying a bunch of extra A330s and running them between SYD/ MEL/ BNE with the back 130 seats being 'Jetstar class'.
So not really a 'game changing' idea. Simply an old idea being revisited.