A few things,
If disney were to built its own airport on the most southern tip of property (im guessing this is where it would be built) would disney buy their own planes to fly folk in, or would they get airlines to fly folk in. Of course there are a few problems, the planes would definetly never be full, and especially now with many folk not flying because of last september, so it would be a great money loss operation to the airlines and disney. And i dunno about airbus, but boeing prices start at about $20m for a 737-500. And i cannot see disney spending this amount of money on a definite loss. The only way it mite work is if they flew to airports that could serve a large area and once or two times a week.
I think though that the airport would work best if they managed to get us Brits in. Everyday from London Gatwick, Manchester, Birmingham, Cardiff, Newcastle, E. Midlands, Belfast, Glasgow there are at least 3 planes with 300+ folk leaving from each of them. Most fly into the new Sanford Airport which opened in 1997 and it is 40 miles away from disney. If you got the carriers such as Britannia, My Travel, Monarch, JMC, Air 2000, European Air Charter it would work. Or, have a disney airlines and those who booked with the WDW Tavel Company UK + US and any others booked with other operators going to disney could fly out in a Disney plane and get a totally disney experience.
I think that up until last september the airports head was just above water with the hope they could get uk tourists in but i think it has gone below the water and the plans sunk.