I don't know what will happen tomorrow - but I can sadly report that on 5 and 6 September, the AA check in agents responded with "Computer says NO".
On the first attempt, we were asking to check bags through from AA flight 1, to AA flight 2, on separate PNRs.
The second was from AA flight 2 (above) to a QF flight, also on a separate PNR, travelling in F (QF and AA) and with OW Emerald status.
The first attempt was really just to test the waters, as we could manage the refusal without too much inconvenience. The second, however, would have meant being stuck with bags at an airport with no Left Luggage service (like most, if not all in the US), from early in the day until check-in opened for a late night flight. That one was certainly worth fighting for.
On the second check-in, the agent ran into a block on her screen, which sent her in search of a sheaf of written documentation that outlined the changed conditions that have been discussed in this thread. She was sympathetic and quite cross about the changes but was unable to over-ride the system. When I gently persisted and explained (several times) that we would not be able to re-check the bags until many hours after we arrived and would be confined to the airport for the best part of a day, she called in a Supervisor, who appeared to be unaware of the changes, but read through the documentation and agreed that it had come into effect only a few days before.
I reiterated the impact on our travel plans and also pointed out that our original booking had been made long before the changed conditions. She eventually agreed to "break all the rules" and found a way to over-ride the system "just this once". We were suitably grateful and appreciative!
Both the original agent and the Supervisor were highly critical of the changes, and stressed that they would apply even to AA-to-AA flights on different PNRs and both said that they hoped there would be sufficient outcry from passengers, to force a reversal of the change. The agent specifically asked that we write to AA (not QF) to voice our displeasure.
So, while we had a satisfactory outcome on this occasion, that won't be the case generally.
The implications for future travel, including long haul bookings we have already made, are quite significant, and will most likely involve some overnight stays in circumstances where we would have flown on immediately. The risk of missing flights while going through Customs and Immigration, collecting bags, re-checking and going though Security and Immigration again, will be just too high. And there will be no protection for such missed flights. (Often, on our itineraries, there would be few options for onward flights on the same day.)
At least this time, the Supervisor's assistance meant that we managed a lovely day of art and food before our onward QF flight that evening.
And we are forewarned for future flights. At least those of us here on AFF are forewarned. Others won't be so fortunate.
What a mess!