Mandating flights seems like a bad solution to carriers canceling flights unilaterally. Why not just force them to provide comparable alternate arrangements and/or pay the passengers financial compensation?
You not taking off means someone else can't land.
No, there aren't for airliners. Most are in the air at any given time.
There's boneyards and mfg. airports, and that's about it.
A possibility would be a non-operating airport in a friendly country - thinking about the new Berlin airport.
Boeing likely finally stopped making the 737 MAX after they ran out of parking space, which forced a decision.
To park even one airliner long-term requires prior permission and monthly payments.
Slots are used to regulate congestion in normal conditions.
Not if the 737 MAXes are hogging all those spots, of course.