That report, however, was published last 2018. Assuming Peter's claim and the several "I lost my btc" threads here are true, what do you think is the current estimate of total lost bitcoin?
Most coins were lost in the early days, so any coins that are being lost now are little more than a drop in the bucket. Also I think it's fairly safe to assume that the majority of people and companies holding significant amount of coins nowadays know better than to lose their password, so the amount of coins being lost over the next few years will probably be rather limited.
Lose the password, not the seed words. And if your wallet is that old to not have seed words, then make a new one and move the funds to it so you can have those seed words. With the seed words you don't need a backup of the wallet either.
Best they can do is track which coins have not moved in a number of years. Since most were lost in the early days, i suppose those with 10 year+ inactivity are a safe bet.
On the other hand, most coins that there ever will, have already been made. So yeah, 18million out of 21, with 120 years to go for the remainder most of which will be minted earlier since production (mining) is designed to slowdown into a crawl.