The quality debate about scientific merit aside, if the U.S. wants to remain "the best", then we need to incentivize the best scientists and researchers in other countries to come here and become U.S. citizens. A lot of famous physicists, mathematicians, and logicians have done this over the past 100 years. Unfortunately, the attractiveness of becoming a U.S. citizen is waning because (1) current U.S. policies on sci…
This may be outside of US control. There are always exceptions, but based on experience of my friends who came to the US from other countries and stayed, scientists generally did not go to the US; they go from something: economic shock, persecution, hungry kids, crime, no science funding (not low, zero), etc. and will to go whatever decent, stable country that would take them. Big inflows of energetic, educated folks happen after wars (e.g., WW2). Collapse of communism made lots of folks from Poland to Uzbekistan search for another home.
Those greatly benefited US but were one-time events that cannot be easily extended. To lead in science a country needs to grow its scientists organically and encourage them to stay in science. My 2c.