Bitcoin will die. Same with any other currency, if there's no one using it, there's no reason for it to exist.
With no one spending Bitcoins, there wouldn't be any transaction volume. With the no one trading on the market, Bitcoins will be worthless.
That will be the extreme result or end if no one will spend their bitcoin and just hold it. If there were no sellers there will be no market. Seller and buyers are necessary to create a market that is founded on supply and demand. Bitcoin though it is a currency it is still considered to be a commodity. But this kind of commodity will not have a value if nobody sells it.
That's right. Bitcoin users are that factor that helped to bitcoin to fly so high and to get developed to the concrete world's market participant. if nobody will spend bitcoin the whole system will fall as the price for bitcoin. So, bitcoin is just have to be spended.