Re: You'll be revived on mars, or worse...
"I do wonder if there's a legal mechanism to retain ownership of an investment portfolio ( managed on your behalf by a firm, of course ) when your brain has been frozen."
A trust would work (IANAL) I expect. In the UK they pay 1% tax every 10 years and allow avoidance of death duties if the beneficiary changes, even if that change is due to death.
I expect the problem would be in ensuring that the day-to-day trust management doesn't help themselves, or that your descendants (or worse, the state) decides to seize the trust, and expect you to file a response.
Perhaps a series of trusts, paying people to watch over other people, that sort of thing.
Personally it all sounds like a scam for extracting a lot of money for rich people with little potential downside. It's not like defrosting tech has been ever shown to work for humans, so there's no actual enforceable contract. Well, maybe the "keep you on ice until you can't pay the bills" part.