The midwest has some great manufacturing industries, but the idea that it is anywhere near ready to replicate Shenzhen on any reasonable timeframe or cost basis

The midwest has some great manufacturing industries, but the idea that it is anywhere near ready to replicate Shenzhen on any reasonable timeframe or cost basis is simply not credible. The expertise, density and investment levels are totally different and cannot be rapidly changed. I'll go as far to say that a devalued currency and/or cheap labor may have been the reason the manufacturing base moved initially, but technology has advanced since that time and Shenzhen has now built up an infrastructure advantage which is much harder to counter.