There are already fabrication facilities in the US and I highly doubt that Intel's fabs would ever be decommissioned. They are far too valuable even if intel doesn't own them anymore.

Now, the US may lag behind top of the line fabrication tech (It already does). But it will never lose it's ability to fabricate chips.

For military applications, unless they start getting really into artificial intelligence (maybe they already are?) they don't need super advanced chips for most of their equipment. Simple micro-controllers are enough for most military applications.