I don't like to deal in probabilities, but I'd reckon a successful revival of a dolphin would count.

No, that's out.

Short of that? Probably nothing, if by 'considerable' you mean 'worth spending my money on'.

Yes, I do mean that.

This means, that no matter what you observe, you always estimate the probability of cryonics working as very low, right up to the point where it does succeed (if that ever happens). Which is equivalent to a priori estimating the probability of it working eventually very low also.

Do you believe that progress will never be made, that it will never be possible to revive a very slowly changing frozen body? In 100 years? In 10000 years? Never ever?