Originally Posted by
Microwave
This is true, though there's no practical reason that TBIT or ORD T5 could not be used for domestic flights. In those cases, the reason they are unavailalbe to domestic travellers is that they are not connected airside (excepting some bus services). In fact, AA will have a direct airside connection between T4 and TBIT in not too long, at which point it will be possible to use the TBIT lounges when departing from T4 (assuming one has lounge access, and unless lounge access rules change).
True, but the TBIT OW lounges might decide to pull the same nonsense that used to happen at the BA MIA A Terraces lounge and not allow access, saying
"oh, you have an Admirals Club located in T4, and you should use the lounge of the operating carrier if one is available in the same terminal."