While the Airbus A321XLR is still in the future - the aircraft hasn't been certified yet, so Airbus can't deliver any - American is beginning the process of switching its existing fleet of A321T planes into the standard, less luxurious configuration.
To be fair, seatback screens are kind of pointless. Alaska Airlines gives hundreds of free movies and shows for free if you use a device while on their in-flight wifi network. I’m surprised that more airlines don’t do that.