D7 Long Haul are currently in the Malaysian equivalent of Voluntary Administration/Chapter 11. Air Asia Malaysia short haul international (under the AK code) are not affected.
Some of the Air Asia group A330s has been handed back to lessors, and it's highly tipped that D7 Long Haul be downsizing to a handful of A330s and the upcoming A321XLRs.
I'd suspect D7 will return to Australia, but with the A321XLRs if D7 Long Haul manages to stick around.
And as for that Virgin Australia - "a 'Value Alliance' member" banner I've posted sometime back, AirAsia group (D7 and AK) is not part of the Value Alliance group, that's led by Scoot, Nok, Jeju and Cebu Pacific with connections to European carriers (Wizzair, etc) via Scoot Long Haul.
EDIT: Seems AirAsia.com are also selling SQ, CX interlines as well. QR also pops up on the AirAsia booking engine via Doha! (that's one long connection).