Your reasoning is faulty, because you underestimate the ability of countries to cooperate. The US could probably even enact a virtually global ban on its own. Yes, some countries could try and resist, or some companies (and criminal organizations, of course) but they would be instantly limited to a much smaller market.
The only thing nations would have to do is make the interface between the Bitcoin economy and the rest of the economy illegal and too cumbersome. Bitcoin wouldn't die, but it would crash hard.
you,handwaiving all 190+ nation states will go along with AND have incentive to do what the all powerful US says...
OKAY, buddy...
Also, and please be honest with yourself, would you like to live in where the US unilaterally decides what private property rights should exist and not? I sure as heck hope you don't want that future.
There's an immediate competitive advantage (in the form of increased business activity & tax revenue) to the first country to adopt clear, consistent rules regards CCs and their use. If a few big countries try to ban it, that competitive advantage becomes even stronger for any country willing to buck the trend.