Am I missing the point or do I not understand your question?
What do you actually mean by filling the void? As I interpret it as: All fiat currencies have gone to smithereens and people lost all value in it and need to start again from scratch, perhaps by using bitcoin? Yes of course in that scenario bitcoin can fill the void, as can seashells, garden peas and whatever else you can convince other people to accept for trading.

In any other scenario, it would be the same question as; Can pesos fill the void in a bank run?