Not only airlines should be worried - if there are no overflights, it means no income to the Air navigation service provider, which mainly lives on overflight charges (unit rates vary from country to country) and the airports themselves face losses. The other institutions which are depending on regular traffic (50 % more or less) are the national supervisory authorities (the CAAs). Off course the model varies from country to country, but a long stand down will ruin the whole industry. General aviation activities cannot be counted as sufficient source of income neither for the ANSPs nor the airports.
Eager to hear the KLM test results and any other results that come out. At least somebody is acting with purpose.
On even a more sober note - it's quite pathetic on our (EU) side to be absolutely hand - tied, and that there are not enough resources to analyze the situation. What for do we have European Space Agency if we still have to call for NASA??!!
