There is enough bitcoins for the 7 billion people in the world. And the price will only adjust because of the demand and it is going to make the price higher and if you did understand what I said, that is going to make every satoshi counts. By that time, 1 satoshi will be not just 1 satoshi anymore for us because that will have a higher value.
We may say that there will be enough bitcoin for the whole population of Earth, but you need to consider how many are interested and not interested in these digital currency. Not all people will use bitcoin, they can't even surf the internet,especially the country with internet restrictions. With it's popularity nowadays, we can't deny that it will be more popular than today, but still, there are always haters.
As long as the market is expanding no matter how many are interested or not. Once bitcoin is starting to make some noise people are going to get close to it. Let's exclude those people that are in that situation it's obvious that they will not have the chance to use bitcoin because there's no access on their place.