The way it will probably play out here is through hiring of foreignors through 457 program which will circumvent any shortage.
If that's a local pilot shortage I assume it's for regionals and lesser paid Australian flying jobs that would see a need to attract foreign 457 sponsored labour?
There must be two thousand or so Australian expatriate command rated pilots abroad and as Tuck Mach alludes to, it will be creative carriers abroad tapping into the resource with commuting contracts if we truly do have a pilot shortage. Even more creative companies may stem their attrition with Australian bases.
The ATO will be onto loose tax arrangements and residency issues well before any negative gearing reforms BTW.