Stamp duty is a significant line item in the state budget, and removing it entirely for a growing share of first home buyer purchases is not a free policy, whatever the politics of announcing it might suggest.
I don't say that to argue against the change, it's genuinely helpful for the buyers it targets, and I said as much last month. But policy that trades away recurring revenue for short-term buyer relief tends to get revisited once the budget pressure becomes visible enough.
My honest guess is this doesn't survive in its current form for the full life of the scheme. Maybe a value cap gets reintroduced down the track, maybe the timeline shortens. I wouldn't build a multi-year investment thesis on this specific concession remaining exactly as generous as it is today.