Most likely the low probability for Bitcoin value to be zero. That's because Bitcoin is naturally volatile and only risky. Altcoin can never replace Bitcoin because it is not independent. The exchange of altcoin prices depends on Bitcoin, it means that, its value is directly proportional to the value of Bitcoin. In addition people do not give importance to this system and create some negative issues or topics that can cause the system to crash and push it to the end. And even I have heard a lot of negative speculation, confidence and confidence. Actually I see and read your topic this is one example of bad news for bitcoin. If investors are reading your topic this may be they will be afraid and think it will happen. But no problem I understand.
I believe that btc will always grow, whether it is from it is technology, whether it is from it is developers, whether it is from it is the price, whether it is from it is the people, and so on. But I honestly do not know about the possibility of Bitcoin's value to be zero. Maybe it will happen, maybe it will not. But if that will happen, I guess it will take a very long time to make it so happen. So nothing to worry about. I do not think that investors will afraid to read this kind of topics. If they learn really careful about btc, I think they will do fine. Just like me, I am also one of some long term investors. I honestly kind afraid sometimes, but I will always keep my faith.