davidjohnson6, whether the catchment is sufficient is a matter of contention but one can imagine the sort of demand they might be looking to attract. London City is expanding fast but serves a wholly different market to the one which Lydd (one imagines) proposes to. Manston has closed; whether the early success of KLM's AMS service could be replicated from Lydd is doubtful given its catchment. Cargo (the former's bread and butter) is dependent on infrastructure which Lydd simply doesn't have. Shoreham's runway dimensions and ATC cover are significantly restricting (putting it firmly in the GA realm). It's very hard to see how investment to reopen the railway to Ashford via Appledore (and thence to London) would be viable. One suspects a competitively-priced GA, bizjet, niche cargo and ad hoc charter operation is the plan. But the resurgence of Southend and Oxford in some or most of these markets necessarily means demand must be localised (even LGW is less than an hour's drive from Ashford) - SEN is infinitely better connected and has still struggled to attract new operators (though this may change as LTN and STN reach capacity).
A mixed picture. LGW is now full enough that (if I remember correctly) EZY struggled to discharge its full flying programme last summer. In Lydd's dreams a loco would use it as a cheap access to a challenge for LGW's easterly catchment; it's not beyond the means of man to have the bus which stops hourly at the turning into the airport (leaving passengers with just under a mile's yomp) actually end up at the terminal. Beauvais doesn't have a railway station; a deal between a based operator and Southeastern could use off-peak capacity on HS1 to connect passengers to a direct bus service. But this is a figment of my imagination, and a long shot at that.
As such I'm at once sceptical as to Lydd's prospects and reminded of the widespread surprise which met the success of KLM's MSE-AMS operation. Without such sprawling infrastructure, if such a service (big if) were to emerge it is easy to imagine that together with summer charters and healthy GA patronage, Lydd would earn its keep. In its absence, one has to wonder.