Devil's advocate: High trust, homogeneous societies are more likely to have more comprehensive safety nets. As trust diminishes (i.e. partisan Red vs. Blue bickering) and the population fragments into large heterogeneous groups, what is there to keep the safety net in place? Why would a bunch of immigrants from Central America, doing the jobs that Americans don't want to do (and at very low wages) want to see a significant portion of their paychecks siphoned off to pay for the retirement of old white people they've never met, in states they've never visited, and with whom they have very little in common?

I think it is more likely that the attempt to try and cover Social Security shortfalls by importing labor will backfire, and that the new citizens will vote against paying more to cover retirement expenses for Boomers and Gen-X.