Karl Marx predicted that the demise of feudalism would mean that wealth would be created anew in each generation. Instead, intergenerational transmission of money and property remains the main culprit for inequality in wealth. Abolishing inheritance would help end inequality within countries; abolishing birthright citizenship would help end inequality among countries, by letting people move for greater opportunity.
Impossible? Utopian? That was the response to those who proposed the elimination of slavery, a persistent feature for most of the world’s history and, like nativism, defended by some because its abolition would benefit Northern capitalists and increase factory exploitation.
Instead of using birth for assigning citizenship, why not keep the boundaries of current countries, open the borders, and use residence to define citizenship, as the 50 states do? Free movement of people in the United States does not diminish the authority of states in our federal system, or the right to participate politically as a citizen of one state and not another. Nor did it lead to the citizens of Georgia moving en masse to Massachusetts.