It wouldn't be a terrible idea. A bench mill, small lathe, drill press, vise, grinder, sander, welder, forge+anvil, and the solar/wind power to run it. It would take quite the investment to be useful in SHTF.
Double the amount of equipment if working carpentry. Saws, chisels, router, belt/barrel sander, clamps, etc.
First priority should be an independent infrastructure to even support a SHTF shop. After that, work with neighbors to build some support and recognition in the established community, this will make you less of an outsider and give them a reason to invest in you in a SHTF situation.