If the flybe 3x daily NQY-LGW disappears and isn't replaced in any form (I still suspect we'll see EZY will at least one daily A319 year-round LGW-NQY) then I could see sense in BA operating one daily LHR-NQY with perhaps some extra Saturday & Sunday seasonal summer flights too.
Since BA seem to be happy to shovel slots onto a 3x daily LHR-LBA and are known to have "slot sitting" frequencies on some of the other domestics such as LHR-MAN I'd think that a NQY could work for them and, as already commented here, be a useful route to fling on some of those summer weekend slots that they don't see to have much of a use for on anything else..