Yes, it's entirely realistic that the US made it to space, and has since then continuously de-industrialized, especially as imperialism has grown.
As for metaphysics, I am referring to the way you are treating the development of socialism itself. Seeing the USSR as the "final" evolution of socialism implies class struggle had ended, and that it is "true" socialism, itself an idealist notion and not a materialist one. When looking at China and the former USSR, both have public ownership as principal, both have dictatorships of the proletariat, both are socialist but suited to their own material conditions.
I believe you have all of these benefits from the USSR. The USSR was indeed fantastic and socialist. Countries are not determined as socialist or not by how closely they resemble the USSR's socialist path, but by how I defined it above.
We reject metaphysics and idealism because they cause faulty understanding of reality, that's why we are dialectical materialists.