To counter this problem, I propose a very simple solution. Once it is confirmed that over 10.00% of the BTCs are "lost", then the earliest 2% should be purged and put available to mine.
What you propose is simple theft. If I want to save my XBT, and bequeath them to my great-great-grandchilluns, it's none of your damnable bidnez.
The idea to purge the earliest 2% (or however many) needs refinement. As jbreher points out it could be in store for grandchildren (however unlikely after 10yrs inactivity)
A mechanism could be discussed to deal with that issue.
e.g more than 10 yrs inactivity 50% can be mined again 50% put in escrow for future claims.
In the UK there is a legal mechanism and rules for inactive Bank accounts after 15 yrs.Also, Banks already got wise to the problem and now charge fees for inactivity (as early as 1yr) This effectively lets them take ALL the money over time.
http://www.moneysupermarket.com/savings/dormant-account-guide/The comparison is not exactly the same as the total useable supply of fiat is not affected as it just goes somewhere else eventually. Unlike bitcoin where the total supply is affected if it can never be used (recovered/replaced) again