It's apparent to me that AA did give up trying to attract the "backpacker crowd" (probably politically incorrect term these days) - the young, hip, Kayaker crowd with no elite status (or maybe Gold) who want to fly back and forth between NYC and LAX for dirt cheap. Years and years ago they flew Tower Air. Now they can fly B6 or pay low fares to help fill up those Delta 767s.
In the third quarter of last year (most recent gov't fare data available), AA had the largest share of the JFK-LAX market at average fares in excess of $500 each way. That high average fare wasn't due to the 128 seats in the back of each 762; that high average fare was due to the 40 bigger seats up front.
We won't know for quite some time whether AA is successful in raising its average fare on the JFK-LAX transcons as a result of its decision to reduce Y seating by 56 seats per flight but my guess is that the average fare will increase. And like happens every day, if AA can't sell those 72 Y seats for the fares it seeks, we can rest assured that AA will cut the price to the level it feels will maximize revenues and/or profits. AA has people on staff with that job description.