I honestly believe we all are aware of this fact already that Bitcoin will soon be completely mined. The 21 million will only be transferred between one person to another in exchange for whatever service.
Soon ? I am sure you know that most of us here will not even be alive by the time we get to mine the last bitcoin, and possibly the kid born today may probably be dead or as well as extremely old when that would happen, so I do not see that as something that can be classified as soon. Also, we have to understand based on what you have said, that this 21 million will not even be in circulation as even by now some have been known to be lost and even in the long run, more will be lost, so let's say eventually when bitcoin even becomes extremely usable, we may not even get to find so much in circulation.
When the BTC is completely excavated. At that time, I didn't know the price of BTC. But at the time, there were no mining incentives. It is estimated that mining incentives are commissions. The market has a big change. Look at the situation that was recognized at that time.
Obviously, if bitcoin is still existing by then which I so much believe it will, the price is not even something we can even imagine in our heads, and may be by then though, 1 satoshi might have become an equivalent to the dollar. The market is pretty much changing each and every day, and there is absolutely no way we can get to not believe that this market would have increased in terms of adoption by then which we all know what that would have amounted to considering the fact that real life usage would even have become a thing in the end.