>>Considering how long it will take to reactivate each one of those planes, it is going to be a very long time before the airlines return to full capacity
Customer demand will not return all at once. It will come back gradually over time. The airplanes can be pulled back out of storage fast enough that reactivation of airframes won’t be the pacing item. The passenger demand will drive the rate at which airplanes are pulled back into service.
There will also be some balance between airlines (the ones that do see demand) electing to receive new airplanes that they already had on order versus the reactivation of stored aircraft. It is reasonable to assume that at least some of those “stored” airframes will never return to service because they simply won’t be needed.
One thing is for sure: any bank or lessor that built a balance sheet on assumed residual value of used aircraft could easily be in big trouble.