Unfortunately, the use of bitcoin as a currency is limited by the technical imperfection of shops, cafes, etc. I would love to be spending their bitcoins, but I just have nowhere to do it. So I'm saving them for now.
True. Bitcoin still needs widespread adoption in our world, to become useful for our daily lives. Now, there are only a select few merchants and online sites which accept Bitcoin for payments. But, as time goes by, I think that adoption will increase as Bitcoin becomes more stable as a currency for daily transactions. The volatility experienced by Bitcoin, makes it unfriendly for merchants and serious businesses. But, soon everything will head back to normal as Bitcoin scales to handle a large quantity of transactions per second.
Sure, Bitcoin could decline in value in a blink of an eye, but it'll be here to stay for quite a long time. Every time Bitcoin becomes cheaper in price, it doesn't mean that it's dead or it has fallen. In fact, it's all the way around it, since it's still performing as intended being a cryptocurrency free from middleman and a perfect store of value.
Therefore, if Bitcoin is still alive as a blockchain network, it will continue to exist in our world regardless of its price.