It doesn't make sense for institutional investors to hedge against "fiat". Because the failure of the current financial system would be catastrophic event for any such investor, at which point his hedging wouldn't help. I. e. the exchange where these futures are traded would no longer be operational.

There's a name for this effect which I've forgotten. But it can be seen, for example, in the markets ignoring the risk of nuclear war during the Cuban Missile Crisis. The reason is the same: there's no use in considering nuclear war in your decision-making, because you'd be dead anyway.