At the very worst case, many of the staff at DSA can be laid off and the doors closed while coronavirus runs its course.
Much as I hate to say it, the value of an airport lies in its built infrastructure rather than the employees. Even if Peel go bankrupt, there will be a time in maybe 2022 when somebody decides to buy the airport from the insolvency practitioner. This is not Ciudad Real - there is a real and sizeable population nearby that want to fly.
The whole coronavirus thing will eventually pass - even if it means waiting 18 months for a vaccine. The 1918 flu epidemic passed and the world economy recovered
The collection of terminal, runway, equipment and road connection is simply too valuable for it to be abandoned forever