I've been thinking about this for awhile, and I realized something. If capital is considered a resource, and we use wealth based systems and metrics to manage it, it really doesn't matter how much is locked in cold wallets. We will simply transact with what we have, and the economic system will adjust dynamically.

Example, there is an estimate that the core of the Earth contains ~9.65 × 10^18 kg (or ~9.65 quintillion kg) of Platinum Group Metals. We currently extract around 70,000 kg annually. We know the rest is down there, we just use what we can get.

So, while it would be better for the velocity of money to have it all circulating, it doesn't really matter.