I just got off the phone with a pro-Obama PDP leader in Puerto Rico. He told me that they expect turnout to be low, as low as 200,000. He also confirmed what others had told me that lower turnout can only help Obama due to the strength of the pro-commonwealth PDP machine under the leadership of Gov. Acevedo-Vila. Publicly, pro-Obama PDP leaders have been predicting turnout at around 400,000.
Afterwards, I called a pro-Clinton NPP leader. He told me that he believes turnout to be 750,000 (34% of registered voters), assuming prior primary data (e.g., the Kennedy-Carter primary turned out 800,000). But he says that he has been telling the press 500,000 to err on the conservative side. He agreed that the higher the turnout, the more likely it will be that Hillary will win.
Both agree that Hillary is likely to win, but the pro-Obama leader told me that depending on turnout, it could be a squeaker.