EF notified me of an aircraft change from a 787-8 to an A321 (Oasis) on a flight I have in under 5 hours. Companion and I are booked in MCE row 6, which are the PE seats used on International flights.
Logged into AA and see that 1.) yes, the aircraft was downgraded and 2.) they moved us from 6AC to 8CD (aisle and aisle). So, they maintained us in MCE. I was also able to change to 9AB for window/middle without issue. There were no other 2 seats together on the whole plane available to assign. A few scattered single seats.
When I check EF, it still shows the flight as a 787, but all buckets zeroed out. Why did they alert me to a change when they still show it a 787? Nonetheless, AA took the flight from 214 to 190 coach seats(including a reduction of 12 MCE seats), so I'm also seeing offers 'starting at $375' to volunteer. We are time sensitive on this trip, so we won't be taking the offers but I think there will be some pissed off passengers who may get to the airport to see their seats all jumbled up - including loss of MCE that may have been paid for. Luckily the 787-8 and A321 have 20 seats up front, so no biggie for those who scored the lie flats.
The aircraft change alert looks both at the equipment code and the Economy seat map layout. One could change without the other changing.