If they cannot be resold to other speculators their price can go waaay down

IF it results in dramatic reduction of home prices, this sounds great at first, but in actuality, it throws the market into disarray, since many sellers and also buyers, and it may trap home owners who need to sell into bankruptcy.

I'm not sure if they could be forced to sell those, the government could, but then that would fall under just compensation seizure. I'm not a lawyer, but it would seem under basic legal theory that you couldn't take those homes.

Tax vacant properties. To high heaven.

Great point. Those homes need to be back on the market for housing prices to come down.