I am not intetested in the economic pros and cons of establishing air services really just what airports etc are out there that COULD.
Chicken and egg situation - an airport which does not have a sufficient catchment area in the immediate vicinity will never be able to support any air service unless it is a "public service requirement" such as those operating to and from the Scottish Islands to the Mainland and similar services in Ireland.
Then you've got to consider the local competition from local rail services - it's often said that if the First Class Rail fare to any destination you want to serve, is cheaper than the minimum fare you can afford to charge, don't even think about it.
Many, if not all, of the airports mentioned would never support regular air services, mainly because they don't have the catchment area, but also because no one could justify investing in the requisite infrastructure.
Sorry to deflate your boat, but it was very intersesting to see all the places mentioned which once had the potential but, for one reason or another, someone missed the opportunity.