This winter has seen 4 757s leave the fleet, G-BYAL, AO, AP and AU.
Next winter sees 4 more 757s G-OOBI,BJ,BRand OX leaving along with 4 767s G-DBLA,OBYD,OOAN and PJLO with all being replaced by new 737-8s and 787s.
More departures planned (though not set in stone) during winter 13/14 and 14/15 with around 14 757s left by summer 14 and ALL 767s gone by summer 15
I remember seeing on this forum a couple of months ago that BYAW was one going for winter 13/14.