1A_Please....
I think he was talking about mainline routes where the only new entrant that has survived is Virgin
Fair enough, but that's not actually what ADBF said.
Jetstar was a relaunch of Impulse Airlines which operated in its own right from 1992 - 2001. And while Jetstar Airways in Australia and New Zealand is wholly owned by the Qantas Group, it's a separate entity under its own right with respect to the Civil Aviation Act.
REX may be a rebranded Kendall/Hazelton, and only till this point have operated regional routes, but it's still an RPT airline that's lasted more than 12 months.
OZJET operated from 2005 till 2008, so was in operation for more that 12 months.
And Compass MK 1 actually survived for a little over 12 months (Compass Mk II didn't though).
Finally, you missed Tigerair...it commenced in 2007 as Tiger Airways and wasn't taken over by Virgin till 2013 when it became Tigerair. So it also operated for more than 12 months.
I know what you were trying to get at though, so all good!