Lots of people in central London say the same thing.
As I have already said, the first debate should be whether or not we want to build a hub that could compete with AMS etc. If the answer is yes then it won't be at Gatwick and the only viable option is Heathrow.
I've not seen any stats or forecasts that demonstrate either of those conclusively.
If it was necessary to provide Joe Public with conclusive evidence of future usage then we would not build anything.
We do however
know that people would be more than willing to use a shuttle service from their local airport to connect onto LH as they do it already through AMS.