This is probably my favorite Fiat, the Fiat 8V. Luckily the United States has decided to back their money with Fiats.
This one is also very valuable. Probably have extra of this one at Fort Knox. Another valuable one is this 8V. 
As long as the United States has an adequate supply of collector Fiats backing the currency, I see no reason for any panic.
Unlike you I do not believe that every currency needs to be commodity-backed. If some people see value in Bitcoin, then that's fine by me; they will transact with those who also see value in Bitcoin. If they don't, they won't.
Inherently, I see no difference between a dollar bill (ink on paper) and a Bitcoin (numbers in a database) in that they're both fiat currencies. You can argue that the "full-faith and credit" of the United States Government means something and makes it better than Bitcoin. Perhaps that argument holds water, perhaps it doesn't. But that's, largely, irrelevant too.
Nobody is forcing you to buy or hold Bitcoin, at least as far as I can tell. So what's the problem here?
P.S.: That's a beautiful car.