They did - albeit voluntarily - "Will the passengers bound for Shannon please remain onboard" - but they didn't, IMO, have a clue who was/wasn't a Dublin vs. a Shannon passenger. They cleaned the cabin around us, then moved me to coach, then moved the coach folks to Biz. Besides, the crew that worked the flight from Chicago got off and a new crew who do the return got on in Dublin.

I was given two boarding passes in ORD - one to Dublin and another for Dublin to Shannon, so I suppose I could have deplaned there but one's return BP is held, already printed, in a very high-tech wooden box with slots for each letter of the alphabet corresponding with the each passengers last name, I guess, at the Shannon airport ticket counter so deplaning there would be neccesary as well.

Besides, what would I say to Customs in Shannon when they saw the stamp in my passport from Dublin an hour before? The DUB-SNN flying time is 28 minutes.

I guess the whole point is that the stop might make this flight easier for AA: it doesn't do much, if anything, for AA's passengers.