Agreed that "replacing biological cells with analogously functional mechanical cells should certainly preserve consciousness," but this is a very limited sort of substrate "independence". This approach makes the difficulty of producing an AI with consciousness-as-we-know-it much more severe. Evolution finds local optima, while intelligent design is more flexible, so I expect AI to take off much faster and more successfully, at some point, in a different direction, rather than brain emulation.

Like dfranke, I favor option #2, but like peterdjones, I don't think it fits under "computationalism".