If no one spends Bitcoin then it will automatically become useless and loose its value completely. I hope we don't get there because that will be terrible and it will spell doom for Bitcoin.
I agree, many people say that if we stop spending bitcoin the price will eventually go up and they can make profit saving bitcoin for a really long time, but everyone does that the bitcoin will die, the demand is going to go up and so is the price and people will get greedy and wait a bit more until no one becomes interested in it.
If there is no use for the bitcoin , the price will drop to zero.