Since the new Govt took office they have toughened the 457 visa even more than the previous one did.
Before an employer is allowed to sponsor an employee under the 457 program they must first negotiate a Labour Agreement with the Department of Immigration and Citizenship. This Agreement sets out the parameters of how many 457s are to be engaged, what arrangements the employer is putting in place to reduce their reliance on 457s over the life of the Agreement in addition to ensuring that there are no unemployed Australians who could fill the role.
I have had enormous problems getting a Labour Agreement up in an area whre there is huge unemployment and the employer is gagging for staff.
Also there are requirements regarding english language fluency and, the kicker in this case, ALL stakeholders have to support the plan. This means that not only does the employer have to support it but any relevant union does as well. I would suggest that it is highly unlikely that any union would support such a scheme given the number of applicants for every commercial airline position.
So I don't think that this is a huge risk.