Never going to happen
Interestig link:
http://www.puertoricoreport.com/the-meaning-of-commonwealth/#.VyaZ-jArKM8
If the Island were ever to gain independence and thus folks there lose their US Citizen, there would be nobody left on the Island by the time it became Independent.
Maybe we should have just let them go, like we did that other territory we gained during the Spanish-American war, The Philippines.