Component suppliers set up shop pretty quickly around the automakers in detroit, but not nearly as fast as they do in China. When major product revisions happen as quickly as they do in the electronics industry, it is a big risk to make changes that may disrupt that. One delayed project can cost a significant amount of money. I think that is a bigger issue then labor costs as things become more automated and more reliant on machinists to set up the equipment. Steve Jobs did speak of moving production back in his biography if there were people with the available skills here. He mentioned needing at least 30,000 skilled machinists to start. We already don't have enough people in vocational fields. This is one of many key problems to bringing production to the US. People seem to think this is all unskilled labor. We don't have enough skilled machinists for the factories we already have here. If and when it does happen, it would be initiated by companies like Foxconn that can do it slowly without disrupting the supply chain. I understand that they are already experimenting with bringing some production to the US.
I'm not sure if a couple hundred acres would do it. That is the size of a company that is near me with 15,000 employees. They would need much more then that. I doubt any former factory sites are large enough. Most former sites are also old and torn down to begin environmental cleanup.