I dont see it, corner is such a technical position, there would be VERY little chance a guy who's never played could start fresh in the code at corner and be anything but a total liability.
And safety whilst not as technical and it's skills, its highly technical in it's understanding of the game and defensive schemes, and not just their role in it, but the whole thing, because the proliferation of zone/man match concepts and how complex the schemes are in general
I dont think an NRL player could go over there and have an understanding of those things without spending like 3-4 years doing it at a college level first. Not because they arent smart enough, but because they havent grown up doing it and the idea of it and all the various concepts that go around it are completely foreign to them.
It's like learning a language, you can pick up enough to get by for a holiday, but it'll take you years to fully understand a foreign language to the level you can hear it, speak it and operate with it fluently.
NFL players would have the same problems trying to play NRL footy