If it's substrate dependent then that just means we'll build new kinds of hardware that includes whatever mysterious function biological wetware is performing.

Discovering that this is indeed required would involve some world-shaking discoveries about information theory, though, that are not currently in line with what's thought to be true. And yes, I'm aware of Roger Penrose's theories about non-computability and microtubules and whatnot. I attended a lecture he gave on the subject once. I get the vibe of Nobel disease from his work in that field, frankly.

If it really turns out to be the case though, microtubules can be laid out on a chip.