If no one will spend bitcoin, i guess the price of this currency will go down or it will slowly lost its value. But i think that will not happen, Now a days people are introduced to bitcoin and if they are interested they will find a ways to earn and spend it. There are also a lot of people who are into trading and gambling, so it is impossible for them to gain or earn something without spending first.
It could go down, but it doesn't have to. Perhaps Bitcoin is seen as more valueable than conventional types of currency and so people are saving their ''good money'' and getting rid of the ''bad money''. It just means that Bitcoin is appreciated as to have a higher value. So to get people to spend their ''good money'' they will have to come with something good.
Such as gold, real estate, silver or other types of goods. It also would mean for anyone who wants to buy or sell bitcoin that they would get or buy at a higher price.
It is like giving someone who's in a country with a low valued currency a euro for the equivalent worth of their currency. Now really that currency is so bad that its virtually worth nothing and the euro will go underground so to speak. Cause the more that low valued ''bad currency'' becomes even less appreciated the more the euro will buy you.