I get the intention, but I feel it may be a particularly extreme comparison, since the US being what it was to the 20th century involved two world wars, decolonization, the cold war, and decades of reconstruction.

Currently, even if China pulls ahead, it doesn't have to mean things getting worse in the US. Contrary to what the current government seems to believe, growth is not necessarily zero sum. Despite Americans' perception of Europe, they too remain competitive in various domains of research. Similarly with, say, Japan.