I didn't realise that the idea was to replace Stamp Duty with land tax. The biggest hurdle I see with that idea is that Queensland, New South Wales, South Australia and Western Australia^*^ have all privatised their land registries. Stamp Duty now goes to private companies and not the state governments. They can't simply replace stamp duty with a land tax.

^*^WA han't totally privatised their Land registrar, but the process of collecting Stamp Duty is private and the proceeds of a land transfer don't go to the government.