For the time being I think US will be keeping 1x daily departure from MAN with 330 ops the majority of the time as happens already. However, the 2x daily 757's do seem to work well for CO as they can offer increased flexibility for their pax with the choice of two daily departure times year-round..... whether US would want to go down this road in the future from MAN who knows?
Are DL still sending in 767s on the JFK run or have any 757's cropped up yet?