If there is a ‘move to outlaw pranks’ – and I couldn’t find that in the article you linked – it will just be a knee-jerk reaction, short-lived posturing. How could ‘Brits’ change Australian laws anyway?
I can see people who revere the monarchy would think it was a distasteful sort of prank on a woman who’s having problems in the very early stages of pregnancy, but the presenters couldn’t have foreseen that the person who took the call would kill herself.