Your theory about the markets represents considerable original research, I don't think it is useful to just assert those ideas as facts or as changes that have happened in the markets. You're obviously aware of specific pieces of equipment that used to have a capability gap that no longer does; you mentioned CNC mills, for example. But just waving your hands and asserting the US no longer has manufacturing sector equipment exports that are difficult to replace, well that just shows ignorance of US exports in that sector. It isn't magic, so it doesn't apply to random things like CNC mills, which are somewhat trivial.
If you ever visit the US you'll find out how funny the trains comment is; we don't really use many trains. It would be somewhat predictable that modes of transport we don't use don't have much investment. It has nothing to do with complacency. I doubt the existing horse-drawn carriages are state-of-the-art, either. Maybe you can sell the sleigh industry on upgrades.
US has 14% of the global machinery equipment market. Export leaders included: construction machinery, engine equipment, turbines and turbine generator sets, and agricultural equipment.