Virgins 737 fleet is starting to get a little older and with 12 aircraft overnighting in SYD every night it would make sense to have a hangar to do some extra work.
And if that hangar was big enough to house a 777 then that would be a good thing as well.
V Oz wont want to keep flying empty 777s to Singapore for maintenance. It doesn't make very good financial sense at the present time.
It would also be a good thing to have another large hangar in SYD that is not under the regime of QF. If QF aren't using them they should be open for anyone