Virgin will never do heavy maintenance here ever. The 'critical mass' doesn't exist, it never will without foresight and without having the capability in place to do multiple lines of heavy maintenance at once. Qantas is only doing it because they're bound by law to do it. Jetstar send 90% of its heavy maintenance offshore. Virgin send 100% of its heavy maintenance offshore.
Foresight is what LTP and ST Aero and SASCO and HAECO show. Build it and they will come. Australia in general has a different mentality, wait for them to come then we will build it only if we absolutely have to.
Just a look at the state of our airports, terminals, transport infrastructure, essential services etc will make that plainly obvious.