Yeah people will still use crypto even if it’s forbidden and that’s just human nature. When anything offers freedom or value, people will discover ways around the rules. Look at how people utilize VPNs or still sell illegal items. In regions where faith in the government or financial system is poor crypto becomes more of a need than a choice and privacy coins like Monero might definitely see increasing use in those circumstances since they’re tougher to track but I don’t think Bitcoin will vanish either because it still has the strongest network and is viewed as digital gold and no I don’t think prices would go to zero even if several nations were against crypto. It would damage short term, certainly but crypto has come too far and is too spread out internationally to suddenly evaporate like that.