ARM also produces core reference implementations. Most ARM licensees’ licenses only allow them to use those in a slightly modified form.
What you’re talking about is an ARM IP license, which allow the company to build their own implementation of the standard. Only a few companies have those and, of those, even fewer actually use it. Apple is one of those that does.
Apple licenses that and develops their own chip, which is then manufactured by TSMC.
So I guess if Intel dies the US will still have a few good CPU design firms, but no manufacturing
Also note that Foxconn (China) assembles the iPhones
Eg https://www.businessinsider.com/apple-iphone-factory-foxconn...