I believe the US possesses the human capital within it to compete with the likes of China in terms of STEM, but American society does not value this ability at nearly the same level as Asian (including India) countries.
Anyone who grew up in the US can gut check this. Which is more prestigious: MIT/Caltech or [insert almost any Ivy League]? The average American will pick an Ivy League. That, not our latent ability, is going to be the seed of our eventual dethronement.
Granted many from Asia might also pick an Ivy League, but I'd wager a lot of money that the proportion that picks a tech school will be much, much higher than America.