If no one spends bitcoins at all then the price of bitcoins will rise a lot .well thats not gonna happen near soon as people reply on bitcoins a lot for their daily uses and people who want to be rich a lot in the future wil not be using bitcoins.
I dont think soo that the price will rise up if no one spends bitcoin since there no activity on bitcoins ecosystem and also this thing would possible if the demand would arise and the supply would froze then thats the time that price will increase too.Bitcoin could possibly make us rich and it depend on how much we do have it.
Yes, the demand of bitcoin will decrease, but I guess people won't make that thing happen because we all want to make the price or value of bitcoin to rise up that is why bitcoin will be continue increasing. And the current price also shows the interest of people towards bitcoins.