Alasdair I think your query might be better in Spotters Corner, but
AFAIK there are no plans to add to the TCX long haul fleet anytime soon. Remember they can use capacity from VKG and CFG if available.
According to ATDB, four A321s due between Nov 2014 and Feb 2015 will not be taken up. They also have G-JMCD/E leaving the fleet in spring 2015.
Things change though.