This is the equivalent of a ponzi scheme if you think about it - unsustainable.
US is a country, not a company - citizens are non-voluntary members - some of them have ancestors that served and died to make it what it is. US did not magically become an epicenter of innovation where Google could be created, it took the whole history of the country to get to this point.
If "more efficient economies" were about to take over, people would stay home. folks continue to come to the US because it is still best here.
some of the "more efficient economies" come from are growing by widescale industrial espionage, made easier by lax controls on intellectual property. People still come here.
Other emerging economies have almost intractable demographic issues that only so much hope can address.
The US would be well served to not blindly repeat the mistakes of other countries for the sake of short term economic gain.