[tlrobinson]

The protocol handles that pretty well by automatically adjusting every 2016 blocks to target one block every 10 minutes. There have been many "breakthroughs" in mining, from CPU to GPU to FPGA to ASIC (see https://en.bitcoin.it/wiki/Mining_hardware_comparison for comparisons).

Or are you talking about breaking the crypto primitives like ECC and SHA256? If there's adequate warning (months? years?) then it's possible to transition to new algorithms, otherwise, yeah, that could be a problem.

[andy112]

I was primarily meaning the crypto primitives. (see http://valerieaurora.org/hash.html for a neat chart of past and present hash functions and their lifetimes.)

Migrating over to "bitcoin-B" or some other variant would be possible, but I would imagine it would be unavoidably chaotic if both currencies stay fully decentralized throughout the process, regardless of whether the primitives break outright or over time.