I don't find it likely. From what I can tell, all of VS' LGW operations head to Caribbean sun destinations, Florida and Las Vegas. I don't see where that fits in with DL at all. I'm not saying it's impossible, but unlikely DL sees any reason to resume operations to LGW merely because VS leisure flights operate from there.
Head in the clouds... yet feet planted firmly on the ground.
Virgin's Gatwick flights to Orlando are package holiday flights sold as "Virgin Vacations". VA doesn't need DL for this and probably would only code-share on the routes. LGW based planes have only 14 Upper Class seats and are mostly Y class with some Y+.