I think it’s important to understand that “money” as it exists within markets exists in a manner to be exchanged and accumulated. Labor vouchers are a type of "currency,” but as they can’t really be accumulated in the same manner money for exchange can be, may make sense in the far future.

It’s mostly a moot point because we lilely won’t make it to the level of centralization necessary for such a system in our lifetimes though, and our successors can figure out potentially an even better system.