The BA ORD lounge has been doing this for some time. AY has chosen not to use the BA lounge and has contracted for lounge space in another T5 lounge. If you have time you can use the AA Flagship Lounge at T3 and since the airside bus service has been restored you can take the bus to T5.
https://www.flychicago.com/ohare/tof...s/default.aspx