So, the economy of scale is still there whether the finances are there or not. If I make 10 pizzas for me and all my friends, Bob fixes all our bikes, Carol goes to fetch water from the well, Dave tends the sheep, etc... All 10 of us are doing our own little economy without money and benefitting from it. What I'm trying to say is there can still be people selling pizza in a collapsed financial system, if we can somehow trust each other to deliver (which is what money does). Maybe we'll end up making our own currency.

All this relies on a basic subsistence right though, us all living in harmony on some commune. If the housing rental system remains in place and demands dollars even though no dollars are available to be gotten, then our landlord is probably going to choose to escalate to violence and won't take pizzas as payment. If the government is going to mandate rent payment in dollars without actually making any dollars available, we have a problem.