But I don't think all governments will prohibit the use of privacy coins, there will always a government that will accept them.
For sure, but the larger countries still matter the most. If USA decides to indefinitely ban privacy coins, it's literally declaring war on privacy. Other countries will see that as a massive opportunity instead and will decide to support privacy coins instead.
However, a ban or an oppression in a large country still means a significant reduction of volume and usage of the said cryptocurrency. Devs from the said country would probably stop supporting the coin's development so they wouldn't be legally penalized.
There will always be alternatives, but how many people would really consider them? Do you think a lot of people'd leave the US in case of a Monero ban? I wouldn't!
just make up some reason like "most of privacy coin are used for criminal activity," and the public will believe it. Remember snowden? how much people actually care about it? the public backlash would be minimum for privacy coin ban.
IMHO, The statement of "crypto is censorship resistant" are not very true, if governments around the world ban it, less people want to be involved, the value will be dropped significantly(massive sell pressure), and the network security would be decreased significantly too.