LAS is obviously doing very well and has reportedly had very high load factors. I could see an additional flight from LGW, but then again I’m not sure about BA duplicating long-haul routes at LGW and LHR.
Can’t see LAX happening from LGW, certainly not all year round.
It may be that post-ATI there might be enough demand to some of the major AA hubs from LGW, but again I think duplication is unlikely and I personally would rather BA targetted new/former routes at LGW.
The strategy has always been LHR is the hub and LGW is point to point leisure, but with a new owner at LGW and (shortly) new management at BA, who knows?