I fully agree with your thoughts bu but I wanted to add 2 things.
1. Even if all states prohibit BTC (a bigg if) there will still be demand from entities not under state control (black market), especially so in ineffective countries (socialist or wartorn or with just big slums). Consequently price won't go to zero because of this.
2. The biggest threat is BTC competitors because there can be infinitely many.
Let's be honest about something about BTC: It's price is where it is because nerds understand mathematics and realize that the Bitcoin goes to the moon if it becomes the new standard international settlement currency. If all or most states prohibit, then this element goes away and the price collapses in a selling spree. I agree that the black market needs a tool, but it doesn't have to be this.
As for #2, I agree that that was a bigger risk early on, but the problem with taking on a second or third currency is it leads to the question of "what stops a fourth or fifth?" it's sort of a recursive proof that could lead you to conclude that either all crypto-currencies will be worthless or one will win. Since crypto-currencies are so inherently useful they probably aren't going to 0, so now the task is finding the winner. And despite ETH being more useful in some regards, and despite Burstcoin or Peercoin having better fundamentals it seems to be that the market has centralized around Bitcoin so out of the CC that exist today, for now I'd put BTC as a 99% chance to own the market 10 years from now if there is one.
1. Even if all states prohibit BTC (a bigg if) there will still be demand from entities not under state control (black market), especially so in ineffective countries (socialist or wartorn or with just big slums). Consequently price won't go to zero because of this.
2. The biggest threat is BTC competitors because there can be infinitely many.