Even if the preserved brain is very different from its original state, it might be possible to reconstruct the original state using future technology.
Imagine if I made an origami animal, then unfolded the paper and handed you the paper plus an origami book with the animal I made. With enough time and care, you'd probably be able to observe the creases and refold the paper to reconstruct the original animal.
Supposing technology continues to advance at the rate it has been -- then by year 3000, the problem of cryonic revival is likely one of statistical inference on possible original brains, with the cryopreserved brain as evidence. Hard to predict the difficulty of that problem in advance.
Imagine if I made an origami animal, then unfolded the paper and handed you the paper plus an origami book with the animal I made. With enough time and care, you'd probably be able to observe the creases and refold the paper to reconstruct the original animal.
Supposing technology continues to advance at the rate it has been -- then by year 3000, the problem of cryonic revival is likely one of statistical inference on possible original brains, with the cryopreserved brain as evidence. Hard to predict the difficulty of that problem in advance.