We will not be alive when the final bitcoin is mined.
It is very likely that none of us will be alive until 2140, unless technology advances so much that it is possible to extend the human lifespan to at least 100 or more years. In addition, some people have decided to freeze cryonically in the hope that one day, with the help of advanced technology, someone will be able to cure and revive them. One of them is the well-known Hal Finney, whose body was frozen after his death, and maybe he will have the opportunity to witness the last mined Bitcoin.
By now we've been experiencing the 19 million bitcoins being mined. For this remaining 3 million bitcoin to be mined it needs more than 100 years.
Something is wrong with your basic mathematics, 19 + 3 = 22. It seems that you have already increased the max suppy by as much as 1 million BTC
Now people start thinking of possible ways to increase the limit from 21 million to a higher number.
Technically there is no problem with increasing max suppy, it's just a change in the code - but it's something that doesn't need to be changed and I hope it never happens. In addition, if you want an alternative with a higher max supply, you have at least a few dozen BTC forks that have that number set at more than 21 million.