Yes they will. But that is why BA closed the route in the first place - to make the LGW route look fatter for disposal.
I said to my mother that I would have to consider two visits a year and not three because the LGW journey is so much more time consuming and expensive for me.
I understand that, to effect this, one of the MAN rotations has been shifted to LTN and I am all well aware of the problems of setting up contracts for a field to handle just one rotation a day (four a week at first).
I would not be surprised if the LGW is reduced to only three a day but the reduction in capacity effected by the Q400 from the 146/RJ may have the same effect.