Great comments. As what happened prior to the amnesty, there is a swarm of gossip going on regarding July 31st. It helps no one, people just need to wait until official announcements.
That is because the 'Amnesty' is just a pardon for overstay and not an extension of any visas. Have to wait and see what the 31st July announcement is.
Depends if you can travel out of Oz and get into Thailand before your visa expires, and that is unknown at the moment. If it looks like you won't make it before the visa expires, get a new one.
You probably won't get a 60 day family extension right now if you have no valid visa or extension to do it with. You will just have to wait and see what happens after July 31st, like everybody else.