One theory I read once is that Australia leads the way with these laws for the other members of the five eyes to eventually follow. Is there any truth in this?
Your scenario is far more unlikely, if not impossible.
https://www.submarinecablemap.com/
Look at the sheer amount of backhaul between just the US and Japan. Now take all that traffic, stuff it down 1/10 of the amount of fiber pairs, with a fuckload more hops. You're telling me nothing will be affected and none will notice?
It wouldn't surprise me though given the CIA coup'd Australia back in the 70s over Pine Gap (their spy facility in Australia).
Easy to see that the war on terror dominated security policies for the last two decades in many countries, not only the five eyes. Officials build their image on that, being tough on X.
Problem is that there isn't any effective opposition because people are afraid of everything these days.