BA are keeping a toehold at Gatwick, as I was told there's commercial consequences which mean a restart in future becomes way more problematic. Hence although all B777 flightrs could operate out of T5 for the foreseeable future, they haven't pulled the plug just yet. Although they may well do soon, as the hangar is being closed and ground handling has gone over to GGS. It's still to soon to say what a post COVID market would look like or when that's likely.
Or possible !