I think it was already announced that another 777 would be heading to LGW for next summer with more deliverys of 787 at LHR.
It looks as if the new Oakland flight will start at the beginning of the summer 2017 season at the end of March exactly the same time the seasonal winter flights to Cape Town discontinue, with Fort Lauderdale not commencing service untill July 2017 and operating three times a week could we still possibly see another long haul destination added at Gatwick for the other days maybe Havana, Seychelles or even St Vincent (a must visit island btw).