It's a route I'd certainly welcome staying at Heathrow.
I often do the LHR/LGW shuffle for Jersey flights and quite often see other (premium) passengers on the National Express or happen to spot the same ones in the Galleries First at LHR after arriving from Jersey.
I reckon there's certainly a market for an early morning and evening rotation to Heathrow in each direction. At least being in NYC now I have the JFK-LGW option....for now.