Bill #150406 authorizes the City to purchase the property from 7777. The Department of Public Property (PP) needs that authorization (per the Home Rule Charter) before PP can negotiate to possibly acquire land. PP has a letter of intent that will be sent to the bank owning the parcel which states that the City will perform due diligence on the property over the course of the next four months or so (soil and environmental testing).
Barring any unforeseen issues, (potential environmental remediation, for example), the City will THEN negotiate with the owner on a purchase. The legislation in question does NOT signal a purchase of the property, nor is the City legally obligated to do so per the language contained therein.
If the City were to acquire the property and then decide not to build, they would have the ability to put it up for sale. Once purchased, the City would obviously be responsible for the maintenance of the property.