I've always understood it was not the absolute runway length but the obstacle limit on 25 which is the problem (although I'm not clear on what the obstacle is!), so if TCX go A.321 they might be hoping for a summer of easterlies.
Alternatively those performance limited destinations could be op as W's by 757's from other bases or with tech stops - seems a lot of disruption to the programme, but do able if they are keen to get the 321's in.