If it was Connex run(), I doubt it would be efficient anyway, but It would be so cheap if it was to be kept in Zone 1/2.
Plus:
-all Vline Travellers get free travel on any Melbourne Public Transport, so you could come from Geelong to the Airport return for only $10.
-It would cost like $2 one way to the Airport on a Two-Hour ticket ex Sthn Cross.

As Long as they dont go off the Idea at Sydney and Charge Megabucks.....