These meat machines aren't necessarily computers, that may be only our best available metaphor (previous metaphors for the brain have I think included telephone

These meat machines aren't necessarily computers, that may be only our best available metaphor (previous metaphors for the brain have I think included telephone exchanges, steam engines and plumbing), and although in principle silicon can simulate anything, in practice not so much: there have been various projects to simulate C. elegans, such as OpenWorm, and they fail because the worm depends on the physics of its environment (possibly including the environment inside the worm) and it's all more subtle than just its nervous system. So yeah, it's reasonable that it might eventually be possible to replicate the human brain in something, once we have the slightest clue how and what.