I'm based in Australia, only half considering making the move to the US if I get an offer from the big 5. I guess I'm only worried if this would have an affect

I'm based in Australia, only half considering making the move to the US if I get an offer from the big 5. I guess I'm only worried if this would have an affect on the amount of positions available from mid sized companies (I've filled my quota of startup experience through internships).