I also believe that no nation could technically "ban" crypto since its anonymous as long as you want to. What they actually ban is you having crypto becoming a public information. Would you be able to turn your fiat into crypto or vice versa from an exchange easily? No you won't be. However you could still own crypto if that is all you want to do, as long as you do not let your government know about it, holding it won't become a problem. This is true for China or any other nation that wants to ban crypto.
The problem with holding bitcoin secretly at China is that the government has control of everything, I am sure there is spyware on every single smartphone used by the Chinese citizens, so the moment you install a bitcoin wallet you are risking the police paying you a visit on the middle of the night.
On top of that world will grow so much around crypto that all these nations who want to ban will not have a chance to ban it in the future, they will have to revert their decision and support crypto even if they do not want to. Why? Because we simply can't be watching crypto grow and help a lot of nations and make them richer while our nation goes to dump, governments will lose a lot of votes if opponents start to promise crypto support, and that is why everyone will accept it eventually.
On this I agree, many countries even if they are against bitcoin will have to eventually accept it if they see it is a positive influence and as an industry that brings a lot of money to other countries, however by the time they do it they could be so far behind that it will not do too much of a difference, this is why what is happening at El Salvador is important as they could be setting up themselves for huge success during the next decades by adopting bitcoin so completely.