So now we are all of a sudden in the "might come to a halt" hypothetical. Ok. First of all, at least 40% of the planes are home-built, so aviation in Russia most certainly will not come to a halt.
Then, how do you picture 500 planes getting returned and leasing companies instantly re-leasing them to other customers to keep their own business afloat? Even if that does happen, worst case, that will reduce Russian air traffic to something like Covid days-level. There are a lot of hypotheticals in this thread, facts on the ground right now are, the planes are flying, cargo ships are delivering and all but 7 banks are moving the money across the borders just fine.