EDIT: I was confused. Confusion now resolved. Disregard this (I don't think it's possible to retract it, and I don't want to delete it in case I wasn't the only confused person).
The frequently discussed quantum lottery thought experiment proposes that a group of people pool their money and arrange for a quantum-random process to determine the winner and kill all the losers. By the Many-Worlds interpretation of quantum physics and the anthropic principle, every person will experience waking up extremely wealthy.
There are lots of reasons not to participate in a quantum lottery, of course, but it seems to me that the general principle is sound. If you go to sleep in a situation where there is only an extremely small chance of waking up, you can anticipate with near-certainty that you will in fact wake up, as long as you survive in at least one of the (virtually infinite) universes in which you exist.
If this is right, then the implications for cryonics are obvious: you can anticipate with near-certainty that it will work. As long as there is a positive Singularity or the technologies needed to make cryonics work are developed without a Singularity in at least one world, you are all set.
(Related: If civilization finds itself in a position to revive some but not all of the people cryonically suspended, we should use a quantum-random process to choose who we wake up, so that everyone gets woken up somewhere)
It seems to me there are a few ways to disagree with this:
1) Disbelieve in Many Worlds.
2) Argue that cryonics is literally impossible, to the extent that absolutely no future world could possibly revive people. I haven't seen this argued much by anyone who has reviewed the literature on cryonics, and wouldn't personally consider it probable, but it is possible.
3) Argue that this also means a few copies of you are likely to find themselves revived in an unpleasant situation, no matter how improbable that is, and that it isn't worth the risk.
Any other objections? As I misunderstanding something obvious?
Anthropics becomes tautological when used to predict the future. "Among the 'me's who wake up, 100% will experience waking up!" This is not at all a substitute for making a decision by weighing outcomes according to probability.