This isn’t particularly recent news but it hasn’t been reported on much for how significant it is. The TL:DR is that many 4G phones use 3G for calls or don’t support VoLTE with Australian telcos. The shutdown will leave a significant number of Australians with phones that cannot make phone calls, forcing them to buy a new one.
I remember when 3G first came out and it was a game changer… everything was fast and responsive. Now days, 3G just seems to have enough capacity to make a call, data is effectively useless if the phone flips to the dreaded 3G. It is like they slowly turned off the tap for it