Originally Posted by pug
Should it not be considered that an airport that relies heavily on revenue from footfall generated by one or two 'low cost' airlines is at significant risk if one of those airlines collapses/pulls out? At the other end of the spectrum there are airports who have diversified their aviation interests and have not put too much emphasis on low-cost airlines, their passenger figures look pretty dire, but are still commercially viable none the less. This is why I believe the thread is null and void.
"Yes" to your question (see Angoulême and St. Etienne in France), but no, the thread is not null and void. Perhaps the thread title is inappropriate in the sense that an airport (the structure, not the commercial entity) may be "marginal" if only referring to passenger numbers, but depending on the management strategy a low footfall airport may be more viable than a high throughput LoCo.
The original question "what does the future hold for these marginal airports?" remains valid - although without the movers and shakers listening in, the discussion will be entirely speculative ...