You could say that about anything. Everything has a total number that will ever exist, even raindrops, it's just a question of whether we know what the total is or not.
In fact I'm looking at a number of raindrops that just got "released from the total supply" outside my window right now.
And as you point out a hard fork could change Bitcoin so we don't even REALLY know the total number there either. Nobody has a time machine.