This article sheds a little bit of light I think:
https://airportimprovement.com/artic...s-one-facility
The project got its start when several rental car lots had to be relocated as part of ORD’s on-going multibillion-dollar airfield modernization program. Rental car lots and support facilities were located in what will be the runway safety zone area for the airport’s new Runway 9C, which is scheduled to open next year.
So I'm wondering if they might at least need to close off the far southern part of G some time in the future? Not sure... they've already moved the cell phone lot from that area and I bet the auto pound will be moving if it hasn't already.