Nothing personal but your view of Govt is very very trust based, while mine is of skepticism. Executive order 6102[1] where the US Govt seized Gold from rank and file citizens is an example of the State's power when they chose to exercise it. This was back in the day when USD was pegged and the Govt didn't have money. So no, not just criminals, in fact, holding gold was criminal. BTC being seizure proof is critical as the power dynamic changes completely.
Moving to crypto or gold after it falls is much too late as your holdings would lose its value, but that's up to you. I can't say what would be used in such a case, but if countries with failing currencies are an example, they moved to buying USD, Bitcoin etc. Ultimately, you move to the best alternative and in the case of fiat, BTC imo is the one but who knows. I don't think you can just create a new blockchain and expect it to all work out after the fact :)