Some of the A321 were very top heavy. If i remember correctly, they had about 32 J seats (Proper 8 rows of 2x2 J seats not european 3x3 Y seats with middle blocked).

The economic crash made them very hard to fill up.

Maybe just maybe we may see them making a return. They should come in handy if IT decide to increase premium seats to places like DXB without putting on a widebody.