If we subtract Satoshi’s 1 million BTC (as Plan B does in his STF2X model), should we also subtract the ~4 million BTC estimated to have been lost?

So that would make total supply around 16 million BTC. Some of these have a private key that is encrypted and the password forgotten, whereas others have lost the private key entirely, like the hard drive lost at the rubbish tip in Manchester in 2013 with a key for 800BTC on it. So the former will eventually be able to be brute-forced in coming decades when quantum computers can be accessed. But the lost keys are lost forever.