1. Not that an expert but there's a possibility that it may fall at zero unless there's some reasonable amount of countries that bans it. If there are still countries that takes it as a commodity I don't think it will fall to zero. There should be a perfectly strong condition before it gets to that level and no one wants to use it anymore.
2. Well, it's game over of course for the whole cryptocurrency sphere unless there are some sort of individuals that will continue later on.

I think I get it when we thought of something that isn't yet fully established like what internet was like way back, there are lot of questions like this and most are just doubtful for a reason. Yet, we are reaping the rewards now from those geeks and believers who continue to believe. We can be those new geeks and believers now. WAGMI.