The ANZAC class for ships of their size are a most impressive vessel.Perth had some work done (I read it was around December 2016). Arunta is the first to undergo the full mid life upgrade which includes more powerful diesels, hopefully a more powerful GT, upgraded air-conditioning as well as other changes.
BAE Systems prepares for Anzac midlife upgrade, as eighth ship completes ASMD
The ASMD upgrade maintains there relevance for many of today's threats and they will continue to provide good service, enhanced by the future mid life upgrade.
They will never be an Arleigh Burke class destroyer, but with their relative young age and constant upgrades they should provide good service for the immediate years ahead, and maybe provide an option if circumstances demand in having their service life prolonged.
At least some will be around for another decade.
Regards S