Zero chance of AA cutting international flying from ORD because of the mechanics. If AA reduces ORD flights to Asia or Europe, it will be because of the stagnant CHI economy, a near-breakdown in law and order among the law enforcement community and better opportunities for AA elsewhere.
It's possible that AA moves B checks to another city, but that's not the same as slashing international routes.
It's more likely that STL closes completely and loses all air service than AA moving its ORD hub to STL. STL is a declining, sad city much like PIT was 30 years ago. O&D to LHR is practically non-existent compared to ORD. Similarly, PHX will never be a major TPAC gateway; the O&D is at much larger LAX.
Internet know-it-alls have repeatedly claimed that Parker will abandon ORD and surrender the market to UA, which is possible, but very unlikely. That would enable UA to build up to a ATL-sized operation at ORD. I suspect that the government would not let UA take over the AA real estate at ORD if AA abandoned it. Probably see a lot more LCCs and ULLCs at ORD instead.
Anyway, AA isn't going to build a hub at STL and reduce ORD. Anybody selling that fairy tale to co-workers should face a random drug test.