Having close ties to Puerto Rico- just want to comment on that- they are not vacillating between statehood and independence- they vacillate between statehood and status quo- which is a associated state to the US, meaning they don't get the economic benefit of being a state, but they get international recognition separate from the US in many aspects.
If we get rid of the rather protective shipping acts, so that Puerto Rico can directly trade with the entire region, they would be MUCH better off, and probably would just keep the status. As it is, they will sacrifice having a Miss Universe and an Olympic team to get the economy back on track. (and yes, those are really huge deals). Their individual culture is a very, very, very big deal.
What really messes up the equation are the Puerto Rican who live in the main US, get the benefits of being represented, etc- but want to keep PR the status quo. I have more than one friend who is that.
That being said, I think they will want to become a state. The laws that are specifically holding them back is making it impossible- like much of the federal payments have been fixed (not adjusted for inflation) since the 80s. It's a pretty unsustainable position for those who can't leave the island. And it's a major reason we have no plans on retiring there.
edit- BTW, the fear of Puerto Rico by the R's is self inflicted based on their racial hate. Seeing who runs the island, they are roughly 50% liberal and 50% conservative. Just like the mainland. For the very near future, until the racists are purged from the party, they will never get support in PR. But if the racist ever figure that out, they can get a lot of the minorities.