I think it'll be harder to kill of what Silicon Valley has become than what Michigan was:<p>Michigan was for at least a couple of periods (e.g. before the Great Depression and after WWII when every industrialized consumer economy's factories were largely destroyed, aside from Great Britain) a or the best place in the world to build cars.  It stopped being so due to bad management at three companies and bad government at the national level (Wagner Act, CAFE).  It was (and maybe still is) a good place to design them, but that requires good management (e.g. look at Toyota's sharp (for them) decline in quality, mostly due to design errors).<p>California has worse government, which has killed the manufacturing part of Silicon Valley (e.g. are there <i>any</i> production fab lines still operating there?), but I'm not sure its government can kill off the design part of things.  To do that it would have to make a middle class existence impossible.  And the very nature of SV companies makes it impossible for bad management to kill the local part of its "industry".