Whats this got to do with VARA? Whether the FIFO worker lives in perth or syd/mel, the roster (contract) wouldn't change. The same number of people are required for the shift cycle, they are all mobilizing through PER regardless.
Well everything. If it all goes to a Perth centric model then you have no real competitive advantage and have to scrap against every other contractor vying for the business. If however say 30% of the contract then flowed onto interstate flights that's a different proposition for a national airline. Charter Operators can't compete against a national airline as they can't offer the connections.