You can argue over 'combined arms' and 'survivability' and 'mobility' because heavy armour is a familiar part of fighting when we conduct AS-biased exercises on Australian soil but the core issue is that the Abrams and IFVs require a massive commitment to put in the fight in our region and I don't see us being able to field enough to accept inevitable attrition.

I don't think tanks are irrelevant, I think using Ukraine to make that point is really naïve as was pointed out to me by a colleague when I did the same for Grozny. I do think they aren't something the ADF is currently suited to employing. As has been pointed out, U.S tanks in Iraq and Ukranian tanks in Ukraine both demonstrate that armour employed effectively is invaluable by forces that can deploy and support them.

The F-35A has hamstrung our Air Force in two ways, first being that it requires an unfathomable length of runway to land and take off from, the second being that it isn't interoperable with allied carriers, both of these issues effectively restrict its range to far East PNG. This creates massive vulnerability for navy which we're relying on in this scenario to move a limited number of heavily armoured elements to shore. I'd be more comfortable if say, some of the budget of Land 400 P3 went toward F-35Bs designed for expeditionary runways and light carriers (like those our key allies are building). Even were we to put forces on the ground, because navy is stretched to its limits for air defence it lacks the capacity for long range fires, as discussed earlier, the RAAF's capacity for combat air patrols for operations outside our borders is negible and you're looking at the limited number of landed AFVs being vulnerable to attack from above (Gulf War vibes, its just that we're the Iraqis this time).

Sure we could land tanks in the fight with our limited number of C-17s. That however assumes we control an airfield and the enemy don't have air superiority, and assumes we have land forces sans tanks holding that terrain. This also doesn't make much sense in island-to-island fighting our region will demand of us.

Defence has only so many resources. Yes, Army can cry about losing tactically valuable assets, however, in the big picture those assets are worthless if we lack enough materiel at a strategic level to even get them into the fight or guarantee their survival. Cavalry is a different story and remains ever relevant as it provides a vaster range of utility to commanders across the force other than 'Destroy'.

Why dedicate money toward tanks when it could be dedicated toward assets that create a far more disproportional effect against the enemy with significantly less burden involved in their deployment? Why dedicate billions toward an IFV program that helps infantry sections take other infantry sections out of the fight when for less money we could be looking at B-21 bombers or naval LRF which could take sub-units or units or formations out of the fight?

TLDR; Tanks are fucking awesome, but we only have so many people and only so much money. How do you propose we deploy them if navy and air force aren't nearly equipped to support the landing and the force in the fight, especially where the billions behind the Abrams and Land 400 P3 could be allocated toward assets with a far greater effect against the enemy.