If everyone stops using it or if in some way becomes wothless, these are the two situations I think of that could make bitcoin die. But I don't know what could cause something like this, people get used to bitcoin and all benefits that it gives and demand is geting biger all the time.
Well, I agree that if everyone stops using bitcoin it will die. However, I think it will not die easily and as of now bitcoin become more popular and famous. In addition to that, as you can see no one can predict what will happen in the bitcoin in future but I believe that bitcoin would not die.
The demand is the life of bitcoin and that is right that if the demand of the people in bitcoin will be gone then it is the final life of bitcoin and it will eventually die but as you say, i also agree that it will be hard for bitcoin to die since it has a lot of demand right now and its users is expanding to its maximum capability.