Maybe it will be mined for some reasons that there could be some losses on the supply definitely the team could add some more coins on it knowingly that there could be a percentage of the losses of that crypto. There could be a substitution to it as we all know that even in fiat money where the physical money is being lost and damaged it will be replaced by other physical money. The team knows how to calculate for it so we will going to trust them.
how does one tell between coins that are lost vs coins that have simply never been moved by the owner?
if bitcoin ever adds to the 21 million supply (for whatever reason) then it would be an alt, not bitcoin.