The true point of no return has to be indeed much later than we believe it to be now.
Who is "we", and what do "we" believe about the point of no return? Surely you're not talking about ordinary doctors pronouncing medical death, because that's just irrelevant (pronouncements of medical death are assertions about what current medicine can repair, not about information-theoretic death). But I don't know what other consensus you could be referring to.
I think your answer is in The Domain of Your Utility Function. That post isn't specifically about cryonics, but is about how you can care about possible futures in which you will be dead. If you understand both of the perspectives therein and are still confused, then I can elaborate.
Why would a self-improving agent not improve its own decision-theory to reach an optimum without human intervention, given a "comfortable" utility function in the first place?
A self-improving agent does improve its own decision theory, but it uses its current decision theory to predict which self-modifications would be improvements, and broken decision theories can be wrong about that. Not all starting points converge to the same answer.
That strategy is optimal if and only if the probably of success was reasonably high after all. Otoh, if you put an unconditional extortioner in an environment mostly populated by decision theories that refuse extortion, then the extortioner will start a war and end up on the losing side.
Jbay didn't specify that the drug has to leave people able to answer questions about their own emotional state. And in fact there are some people who can't do that, even though they're otherwise functional.
There are many such operators, and different ones give different answers when presented with the same agent. Only a human utility function distinguishes the right way of interpreting a human mind as having a utility function from all of the wrong ways of interpreting a human mind as having a utility function. So you need to get a bunch of Friendliness Theory right before you can bootstrap.
If you can encode microstate s in n bits, that implies that you have a prior that assigns P(s)=2^-n. The set of all possible microstates is countably infinite. There is no such thing as a uniform distribution over a countably infinite set. Therefore, even the ignorance prior can't assign equal length bitstrings to all microstates.
Use a prefix-free encoding for the hypotheses. There's not 2^n hypotheses of length n: Some of the length-n bitstrings are incomplete and you'd need to add more bits in order to get a hypothesis; others are actually a length <n hypothesis plus some gibberish on the end.
Then the sum of the probabilities of all programs of all lengths combined is 1.0. After excluding the programs that don't halt, the normalization constant is Chaitin's Omega.