This is somewhat true, but don't underestimate the capacity of the USA. The Department of War (feels good to say) has been buying up extra capacity for decades on all kinds of things. We (as in the place I work at) develop products that use rare earth but also several other technologies that would be considered "hard to source" and "no longer produced here"; however, DoW purchasing has never slacked and they've been buying up large quantities of product since before I was born (so go back to at least the 70s). The stockpiles of spare parts, component parts, and finished product are enormous; then you get to the equipment that is actually in-service right now, which is entirely separate and has its own redundancy systems in place that don't touch the stockpiles. And understandably so, you'll never hear about that.
There is still an "end point" where stock would run out. But that is a lot further off than most people would realize. And we've been trying to reverse course for a few years now. Progress is moving back in the right direction and if you're an American, you can thank your predecessors for thinking ahead and buying things in bulk.
It is a really fascinating topic of discussion.
