No highly qualified tech worker is going to leave a job rich environment like Silicon Gulch to move to a one-employer town in the middle of nowhere. The companies know this, or should, and realize they are going to have to grow their own. They would like to get some help from community colleges in terms of specialty training classes and, probably more important, math. Not math for the sake of numbers necessarily but rather an approach to problem solving. There will always be a surplus of problems.
There are other problems, notably supply chain. Specialty gases, specialty chemicals, specialty facility equipment (DI water production for example), filters, UV lamps, a whole shopping list of things that won't be available locally and the profit from dealing with a single customer (or short list of customers) won't entice a local supplier to get involved.
Hazmat disposal is another issue as is sewer treatment capacity. I don't know how wet the processes are today but even a modest fab would use about a half million gallons of water per day back in the mid '80s. I couldn't imagine what a mega-fab would take based on those processes.
Power requirements could be quite large if diffusion furnaces are still part of the procress. Given the internal heat gain (substantial) the HVAC systems are quite large. Thousand ton chillers (more than one) are certainly in the mix. Water and sewer systems will be strained no matter where the site is placed.
These issues are not unknown, the companies just want somebody else to help pay for them.
Don't forget specialty training for first responders! Often the companies provide a level of response but that won't include large scale events. Does the Building Department even understand what they are approving?