>Another problem is the lack of guarantees that 100 years later the same company would care ...
Only as a curiosity, I always wondered how the payments are arranged with such a company.
I mean, is it a lump sum paid at the time of the freezing or is it monthly (or yearly) subscription fees?
If the first, the risk might be that once the company has made enough money, it simply folds, with the second, who is going to pay the subscription, heirs, but then they could change their mind or die themselves, or spend the money on something else.
Probably there should be a trust, or an escrow service of some kind (which BTW might have the same 100 years duration issue), but even in this case, how do you calculate the amount of money needed on it, will the money be invested in such a manner to compensate for inflation, what would happen in case of a financial crisis, etc.