Yes the future at LGW is bright orange, sadly.
However the noises coming from BA @ LGW are promising, im hearing suggestions that BA are moving at least 1 A321 to LGW, as well as more A320s and several more A319s.
Yes these will replace the 734s but replacing a 734 with an A321 is quite some replacement.
They are also moving 1 extra 4 class 772 over to Gatwick to increase rotations on existing sunshine routes.
As for NYC ex LGW, never say never. I don't see BA trying it in the next couple of years but eventually as you say they will.
Whats the difference, well BA have significantly reduced costs at Gatters, they could also fly the correct aircraft to NYC, and I do say NYC, that does not have to be JFK, BA do have a decent presence at EWR.
The only people that will know the numbers are those who work for BA, they will know how many people connect LGW-LHR and onward from LHR, with extra flights going to JER when BE pull out I expect the cross London connections to increase, and I suspect that sooner or later BA along with the AA JV will add a flight ex LGW into an AA hub, be that JFK, DFW etc.
Running split operations between LHR & LGW has proven a positive move for LAS as each airport targets a different market, too many people were trying to fly BA and they didn't want to use extra slots on the route so it was perfect for LGW. The same could happen with other routes if extra rotations are needed.
Who knows, but one thing I do know is that BA LGW seems to be on the up, long might it continue, it will be interesting to see the route and fleet make up at LGW for summer 14.
cs