It is to ask if there will be a time when it will be scarce and that is simply a no. What happens to this question of op is about demand and supply. According to economic terms, a seller will be ready to sell at a particular time and price. The time is operational and capable to further push price up. So you see the worst that can happen is that bitcoin price will keep increase because of the value that will land on it as more demand for it will be made. Bitcoin is broken down into smaller units as satoshi, mbtcs and not just a coin.