It has been reported that Virgin Atlantic will terminating their London Gatwick-Las Vegas McCarran service for flights after March 31 2019, replacing the service with a new route operated out of London Heathrow.
Virgin Atlantic currently operates 7 weekly flights to Las Vegas using B747-400 equipment.  From March 31 2019 the carrier will launch a new service out of London's largest gateway (LHR) which will be operated using B787-9 aircraft.