There would be no reason in particular for BA to give GB any routes from LGW as they have just recruited CC. Also at LHR we are realiably told that a number of flights short/long will revert to LGW next summer due to the inherant caos this summer.
It may be that whatever is announced the BA/GB will be related to european changes. Within euroland it is rumoured that BA intend to withdraw all directly employed BA staff and make the whole ground op with the exception of CDG/AMS third party managed.