No Sponsor,
I asked the exact same question of a BA FO yesterday. Apparently traffic has picked up quicker that BA expected and the 757 phase-out rate has been reduced. Unfortunately too many crews have already been moved to other fleets and BA are trying to make up for the resulting shortage in 757/767 rated crews.
(BTW the FO (an Airbus pilot) told me that one of his mates had recently transferred from the A319/320 fleet to the 757/767 fleet to get some longhaul flying and was shocked at the avionics in the 757 cf with the Airbus. (Now that will start another Airbus/Boeing debate!!!) And as I spent 4 hours in one of BA's Airbus sims yesterday I know what he means! Automatic trimming - no more fiddling with trim switches!