NQYGuy - I think you are missing a very big trick in your post. It isn't all about convenience of central London - the LCY route offers that and hopefully it will last. BUT.....The withdrawal of FR from STN leaves a vast area with a sizeable population without a link to Cornwall. For much of Essex, Herts, Cambridgeshire, Suffolk and possibly some of Bedfordshire and Norfolk, getting to LGW time-wise to fly to Newquay makes no sense whatsoever, and that is before the cost of trains/driving/parking. LCY is only a suitable option for some of these people who have direct rail links to Stratford, but you are relying heavily on the trains which are very unpredictable in these parts (strikes, constant weekend maintainance).
There is definately a market for an off-peak service to STN from ASW that would cater to leisure travellers in the East prepared to pay that bit more than FR charge for the convenience. Especially as the timings of FR's flights this year have been dreadful - too early most days! Possibly even a once or twice a week service to Norwich would work too. Whether that would happen or not is another matter, but they are feasible. I would also say a single daily LTN flight by BE would also be feasible.