You can't seriously be asking what will happen to the value of bitcoin when a particular event happens after people have already stopped using it and aren't ever going to use it. If nobody uses Bitcoin, its value is zero, regardless of all other factors. Bitcoin has value only because people are, in fact, using it right now. Some are using it to buy things and some are using it as a speculative investment, but it doesn't matter what they're using it for; as long as Bitcoin is useful for something, it has value.