Cryonics working requires most of the same "black swan," and providing large lifespans is heavily correlated with large lifespans for ordinary people. The chance of cryonic organizations failing increases with time (among other things, their financials are rickety, and there have been past failures), so the much of the chance of cryonics working depends on big technological advances happening within a century.
I would say that conditional on cryonics working (which is a major thing to condition on), the chance of the "black swan" (which I would define more precisely) is over 10%, which is enough for it to do better on that front. And the black swan can occur even if the cryopreservation process doesn't store the key information, which would further increase its advantage.
If we assume cryonics requires advances within the century, it's still true that those advances are more likely to come LATER than sooner. Cryonics means I survive whether the advance comes tomorrow or the day before the company would have thrown in the towel.
So the odds still favor the cryonaut over the African kids, because the cryonaut has longer for that advance to occur. Also, the cryonaut is someone who has the resources and culture to invest in a long-shot like cryonics DESPITE it being unpopular and fringe, whereas the African kids are unlikely to ...
I am not currently signed up for cryonics. I am considering it, but have not yet decided whether it is the right choice. Here's my reasoning.
I am very sure of the following:
1. Life is better than death. For any given finite lifespan, I'd prefer a longer one, at least within the bounds of numbers I can reasonably contemplate.
2. Signing up for cyronics increases the expected value of my lifespan.
But then I also believe the following:
3. I am not particularly exceptional among the set of human beings, and so should not value my lifespan much more than that of other humans. I obviously fail at this in practice, but I think the world would be a much better place if I and others didn't fail so often.
4. The money it would take to sign up for cryonics, though not large, is enough to buy several centuries of healthy life each year if given to givewell's top malaria charities. Since on average I expect to live another 50-60 years without cryonics, the investment would need to increase the expected value of my lifespan by at least 5,000 years at minimum to be morally acceptable to me.
5. There is a chance we'll discover immortality in my lifetime. If so, then if I signed up for cryonics the payout is 0, and the people who died because I bought insurance instead of charity are people I could have saved for far longer.
So, what do you think is the probability that immortality will be discovered in my lifetime? What about the probability that, if signed up for cryonics, I will live into the far future? These priors would seem to be the key for me to decide whether signing up for cryonics is morally acceptable to me.