The problem is determining what the land is worth. If you use a periodic market-based auction system (the only known way that could possibly yield accurate prices), then you give the government and the wealthy extraordinary power to kick people out of their residences, even ones in which the tenants built the house. Good for the collective perhaps, but terrible for individual autonomy. This could be mitigated by auctioning off longer length (~say 30 year) leases, but you can end up with huge value mismatches after 30 years of change, just like today, and I suspect there would be other unintended consequences. For example, things wouldn't be built to last, they'd be built to generate as much value as possible before the lease is auctioned off again.
And even then, you haven't really determined what the land is worth, since any rational auction participant is considering how much money can be made with the existing improvements on the property.
That being said, I hope they do try it in Detroit, since I have no stake in the city and it seems like it has more to gain than to lose from such an experiment.