One thing that probably has not been thought of, during the creation of BTC, is that the number of Bitcoins will be slowly reducing to zero. There will be, in some time, 21KK BTC, but what about bitcoin that get lost? I mean hardware malfunctions. Wrong address transfers. Lost passwords. Forgotten wallets etc.

Do we know, how many of all Bitcoins is in circulations at this moment? I mean we can count the number that indicates how many it should be. We however do not know how many of them is inaccessible.

One day it might be a problem, but probably not the problem of our generation. Still statistically that says bitcoin cannot survive.