I've been thinking a lot lately about the idea of creating a very large facility for cryonics storage. The main reason for this is that a larger vessel costs less per unit volume. Whenever you increase the diameter of a sphere or cube by 10, the surface area (which is what determines how much heat enters) goes up by 100 times, but the volume (storage space) goes up by 1000 times. So keeping 1000 times as many patients frozen only costs 100 times as much -- it is 1/10th of the cost per patient. Storing one thousand patients is 10 times as cheap (per patient) as storing one, and storing a million patients is ten times as cheap as storing a thousand.
Suppose your long-term costs are $200/month for neurosuspension in a small dewar. Store 1000 heads and you can store the lot for $20,000 per month, which is $20/month each. Store a million and it costs them each only $2/month. And that savings is from geometric efficiency alone...
In addition, you can add extra insulation with less proportionate effect on surface area. If you have an inch of diameter added as insulation, that is 10% of a 10-inch diameter vessel, and adds 10% greater surface area. Make that vessel 100 times bigger and you're talking 0.1%. The cost of an inch of insulation is brought down by making the vessel bigger. Thus you can choose a cheaper form of insulation (e.g. spray-on polyurethane foam), or simply use more of the really good stuff (layers of reflective mylar suspended in a vacuum).
Another advantage is that liquid nitrogen need not be used, at least not throughout the vessel. The ideal temperature for storing vitrified biologicals is not LN2 temperature, but actually slightly above it, at -130C. Cooling lower than that can cause more cracking. But all that aside, practically speaking you could save a lot of money by running a large facility at a slightly higher temperature, as less heat would leak in. The time buffer created by LN2 could be reblicated by having large amounts of thermal mass. LN2 could also be kept inside the vessel in a smaller storage tank under a slight amount of pressure, as a backup in case of catastrophic loss of coolers.
There are disadvantages to building a larger facility. For one thing, it is harder to keep it in a secret location. This could make it a bigger terrorist target, particularly if we were to construct comething like a billion-person tank. On the other hand, security is yet another thing that could be increased dramatically at a reduced cost per patient.
The biggest obstacle I can see is that in order to pay for it, you need a heck of a lot of people to be signed up for it. They would most likely have to be paying for it before they die, because you need enough money to fund it as soon as it goes into operation.