Bush, like some congressmen, says Puerto Rico should have a new up-or-down plebiscite, but even if this would yield a new result, it would be reckless. In any referendum, permanent change of status should hinge on some supermajority level of support, as, say, constitutional amendments do. We do not want ambivalent states.
If Puerto Rico became a state, its economy and culture would be incredible outliers: It is twice as poor as the poorest of the 50 states, and it would of course be the first Spanish-speaking one. Statehood would remove some of the competitive benefits the island currently enjoys — protection of the United States and its laws without paying income taxes, for instance — in exchange for an inordinately generous welfare state. (One important economic policy exported from the mainland, the federal minimum wage, is believed to have had devastating effects.) The territory is currently stuck in a deep economic malaise, driving large numbers of residents to emigrate, but what it needs is structural reform, not statehood.