planning, what would the scope of that be? Who would administer, and how, infrastructure investment or publicly funded child care in the countries our immigrants come from, like Mexico or the Dominican Republic?
[WS:] You seem to confuse administration of a territorial unit with administration of people. You do not need to administer child care centers or schools in Mexico or the Dominican Republic - only those located in the US. As far as unemployment insurance or social security programs are concerned, again these are not free welfare handouts to everyone who shows up, but employment-based insurance programs - so the fear that somehow every person from Mexico or the Dominican Republic shows up here to collect a welfare check is a red herring.
BTW, if you accept the notion that the proper role of the state to enable people to earn their living instead of giving them largely symbolic handouts - the fear that open borders would undermine welfare state would be totally unfounded. How would, say, a Mexican immigrant cashing in his social security check that he earned working in the US economy be different from anyone of us doing the same? If anything, the prospect of social security being solvent in the future would be greatly enhanced with open borders policy http://www.ssab.gov/brief-1-immigration.pdf#search=%22immigration%20social%2 0security%22
Wojtek