To the example of factory and 50 year cycle of auction and potential eviction. If noone else wished to take over the land on which the factory stood, well then

To the example of factory and 50 year cycle of auction and potential eviction. If noone else wished to take over the land on which the factory stood, well then the factory owner renews the lease for another 50 years. If there was somebody who wished to own that land and offered higher price, well they'd win the auction. However they wouldn't suddenly own the factory. They would still have to pay the price of the factory to the previous owner, much like it is done today. If they didn't want the factory, only the land under it, and they won the auction but didn't pay for the factory, then that would result in a deadlock situation. The original factory owner would stop production, but the new owner would be prevented from using it either, but would be stuck with the rent payments for the land under the factory. Most likely he would sell it back to the previous owner or just not bid for it in the first place. Only if he really wanted it that much that he would pay for the land rent to the government and price of the factory to the previous owner, he would get it. And that is pretty much how it works today, so nothing really would change.