nbn
Sounds like the BA rumour mill is going flat out and you've been the victim of some of it...don't plan on all BA's work being out of LHR for a very long time, if ever . As others have said, even if T5 was big enough to cope with all of BA's LHR and LGW flights there simply are not enough take-off and landing slots i.e. runway "space" to cope.....
OTOH I'd rather work at LGW than LHR...good luck wherever you end up.