Newquay will never make up the £3m or so shorfall in it's numbers through aviation-related revenues, they have to be much more adventurous with the property portfolio and the land they've gort there - things like a top end aero park with homes with pools and hangars for those wealthy private aviators, exhibition, conference, film studio facilities, some motorsports activity etc. etc. The weather's better down there in terms of sunshine than most of the rest of the UK, the beach is minutes away, there are a raft of trendy new top end hotels etc.
The demographics of the people who go down either for holiday or to there second homes is very broad in wealth terms - half the home counties set are down their as often as they can get down.
With Gatwick's links pulled next year, what you need is runs to the likes of Oxford and Cambridge on the London region periphery, where the money is, where the second home owners come from. Southend/EZY will suffice to a small extent but ideally one needs a London City run again - Fridays, Sundays, Mondays, trouble there is the costs.
However, its the property development that can only subsidise the costs of runing what is pretty significant infrastructure - it's not a little runway. You can't just rely on pulling in aviation maintenance or support companies as the world and their dog are trying that game all over the rest of the country.