Unfortunately at the same time it seems like JFK - SFO has become all 757, seems like DL is keeping the premium focus on JFK and LAX but dialing it back on JFK - SFO (understandabe given UA's strong position).
Mostly news for J/D1 (better seat though 2-2 instead of all-aisle) but bad news for Y. Iprefer the 763/764 with 2-3-2 vs. the 3-3 of the 757.