There's an interesting story over at Deutsche Welle concerning airports in Germany. The emphasis? Germany would appear to be peaking out over airports.
Added up....there are around thirty-seven airports with service on a daily basis (Wiki's stats). There are around another twenty airports, which mostly serve as sites for private owners of aircraft to park or operate their aircraft out of.
Most of the big airports....everyone is familiar with (Berlin, Hamburg, Frankfurt, Stuttgart, and Munich). Then you have the oddball airports. Hahn is a good example. Hahn operates mostly as a hub for Ryan Air. The operators of the Hahn would like to have more operations and have more than enough structure to handle that.....but so far, there's been little interest for other companies to operate out of the airport.
Sylt Airport operates mostly for the tourists or the upper crust residents of the region. Being an entry point to the island area....it's not exactly a place that most Germans would ever use.
Zweibrucken Airport is one that chiefly gets operated for tourists making runs down to the Canary Island, Greece, and Spain. On a daily basis for 365 days a year....there's probably only four daily flights out of the airport. But if you go down in May or June....there's probably another six to ten flights a day operated for tourists.
Of course, all of this drifts back to the question that Deutsche Welle brings up....profitability. I think if you took away the state and federal funding....the majority of airports in Germany would be shut down. There would probably be around eight airports able to run on their own, without the structured assistance. So there in....lies the problem. The public is sponsoring these airports to a significant degree, for the benefit of a certain group of society.
With government funding always in question....there's this future problem sitting out there. There are various hints that funding will be curtailed at some point in the next couple of years. For Hahn, without more business....they won't be able to lift themselves off the necessity of government funding. Ryan Air built a huge hub out of Hahn, but other than Ryan Air....there isn't much to brag about. Some thought that FEDEX or some other cheap carrier would have moved in and taken advantage of the lesser tax rate of the airport. That hasn't happened.
So, this bring us to air travel in 2020 within Germany. I'm mostly of the opinion that ten small regional airports are going to be cut off completely from federal funding, and probably even see their state funding decrease. Hahn itself might survive on....maybe with some unusual deal with China or Russia. Whether the Berlin Airport is ever finished....may dictate whether several regional airports around Berlin survive on, or get pushed into just private owner situations.
There's only enough business for a certain number of airports to survive on....and that's it.