[pvg]

Cryptanalytic research is the fundamental thing that broke SHA-1, not simply the increase in available computing power. So that's not really a 'reasonable assumption', if it was, we could 'reasonably' assume SHA-512 will never be broken.

[greiskul]

The point remains, since computing power increases, and cryptanalytic research advances, we really should make sure software that depends on cryptographic hashes has a reasonable way to move to different algorithms. At the very least we could add as a prefix to the resulting hash the name of the algorithm that generated it when we store it.

[pvg]

The advances of research and computing power are vastly outpaced by basic things like digest size. If you came up with a complexity reduction of the order of the one developed against SHA-1 for SHA-256, you won't be able to find any SHA-256 collisions.