> scenarios of what could happen

What could happen?

In my case the home address is old, not my current one, so I dodged a bullet there. That leaves name, DOB and drivers license number. How can those 3 things alone be used?

Email and phone were taken, but nobody can use those if verification is needed. And I can easily change those details in the various places they are used.

I'm quietly confident that because my home address is my old address, and therefore not associated with my drivers license, I'm in better shape than millions of others in this breach.

I'm still angry about it! The email from Optus was tone deaf. They worded it like they are the victims, downplayed the importance, and even ended with "warm regards".