Libertarianism in the economic sphere is only sustainable when other voters are libertarians like you. Amnesty will conjure up millions of new voters from Latin American countries who think Chavez-style socialism is the answer. The reality is that the people we're importing from the region vote overwhelmingly Democratic, which is what you'd expect from people who are eligible for Federally-mandated ethnic quotas, which are Jim Crow in reverse. Southerners supported Jim Crow for close to a century because it provided concrete benefits. Why would we expect Hispanics to react any differently?
Libertarianism in the economic sphere is the free market which is utterly sustainable as long as people want to be free or at least recognize what’s in their best interests and don’t allow government to muscle in on their affairs. Good examples are the people of Chile or Estonia or America before the 1930’s. The free market doesn’t require political, religious or personal agreement, only voluntary cooperation based on self interest. It’s a kind of heaven on earth.