Do you mean:
...realistic chance to restore, within the next 20 years, an otherwise-dead-but-cryonically-preserved brain in such a way as to preserve the associated person's continued existence?
or:
...realistic chance to preserve, within the next 20 years, an otherwise-dead brain in such a way that it can at some later time be restored with the associated person's continued existence preserved?
I think the chances for the former are very, very small; the latter chance is slightly better (there could of course be some technical breakthrough), but let's say I wouldn't bet my life on that either...
Again, I'm no expert in these matters, and I'd be delighted to see some research that shows I'm overly pessimistic.
Having been diagnosed with cancer last year, writer Christopher Hitchens has died. He was known as as an outspoken atheist, which is not, in itself, identical to being a committed rationalist in any systematic way. Even so, he seemed to have the virtue of moral courage, the willingness to speak the truth as he saw it, without fear.