I think if he is still below par after the Australian series, then he should definitely be shown the door. International cricket is not a platform where you are supposed to find your rhythm.
If he doesn't perform he has no business playing. He needs to be treated like just any other bowler and the excuses are falling short now, he has been playing regularly for a year.
I have no hope from Amir on flat phattas of Australia. If he can't do it the seaming conditions of New Zealand and England then he won't do it in Aistralia either. The likes of Warner must be licking his lips at the prospect of facing him.