Thats 12M divided by .463476= 5.5617% of bitcoin potentially dead in lost wallet addresses. Now add .5% a year (average loss of currency through death (sudden or otherwise) NOT including lost wallet addresses for other reasons and in 20 yrs from today 15% of bitcoins lost 40yrs 25% + 80 yrs 45% + approx. Here is one of bitcoins major flaws.. NO method of identifying and replacing lost coins which is unstable and potentially inflationary.
As bitcoin value keeps on rising i don't think that this trend will continue. People were losing and forgetting about their coins back when they worth nothing. Today if you have 100 bitcoins normally you 'll have 100 different backups and failsafes in case that something happens to you