Considering a 2.5% increase in GST would raise about 1% of GDP on its own so I highly doubt a land tax would be enough to completely offset the GST. We're not completely in the world of fantasy here considering
others have made this proposal.
To be honest a full blown Henry George style land tax might be a good idea (though obviously not as the only tax as he proposed).
A
gain key to stress that most necessities aren't taxed under GST and that when it was introduced it abolished a number of already existing sales taxes and came with an increase in welfare payments. I guess a the burden of a 2.5% increase in GST could be added to welfare payments. Also female hygiene products should probably made exempt as well. Compensations could also be made if they decided to broaden to GST to include more things.