To be clear, we had a bimetallic standard, silver was then replaced by paper gold, and the state then seized the remaining stock of privately held gold. It's hard to say that gold won, except from the perspective of the state.
https://github.com/libbitcoin/libbitcoin-system/wiki/Reservation-Principle
I mostly agree with you. Solving the Byzantine Generals problem is even more momentous than I think many of us realize. PoS does not even compare. That said, I do believe that there can be more than one implementation of Bitcoin with atomic swaps between them. This is a similar notion to the bimetallic standard.
https://github.com/libbitcoin/libbitcoin-system/wiki/Substitution-Principle
Money does have a tendency to converge on a single network, but this effect is much weaker than it is for communication networks.
https://github.com/libbitcoin/libbitcoin-system/wiki/Network-Effect-Fallacy
The convergence tendency is counterbalanced by the utility threshold.
https://github.com/libbitcoin/libbitcoin-system/wiki/Utility-Threshold-Property