Delta, at its website on Economy Comfort, indicate they have already deployed 757 with Economy Comfort on its JFK to SFO & LAX flights. Looking at the schedules and its seat maps, it does indeed show 757-200 deployed with Economy Comfort. I believe they are 75E with 16F and 12 Economy Comfort (ABC side of the plane) for Row 19, 20, 21 and 22.

With less seats in F cabin and increased competition for a chance at that F upgrade, it's debatable whether this aircraft would benefit your travel. Other than this market, it will be a hit and miss for this aircraft to be assigned to a different routes.

Jiburi