If ever no one is buying Bitcoin anymore the price value will be drop for sure,it rely to people uses Bitcoin if there is low of demand and high of stock the price value will decrease,if it will continue to this case it will last into less value.For now it is impossible to happen because people already know how important bitcoin is,and it is also a way of long term investment.
I do not think that it is going to happen so soon, because bitcoin is still in its initial stage and there therefore still people are accepting bitcoin and investing money here, therefore it is not going to happen so soon. In fact bitcoin will continue increasing its value and even the bitcoin users will continue increasing for a long long time.