“Often it was the stuff unrelated to the assassination but intimately related to how intelligence agencies do their business. There were practical and institutional reasons it was important for them to keep that stuff. They were very protective of relationships they had with foreign intelligence sources or situations where they might have a base or a station in a particular country.”

As a person who has worked with these records extensively, I believe this quote sums up what will be found and will be the most revealing information when the records are released in 2017. Sure we may find out more about the assassination itself or anything earthshattering, but the real potential for a greater historical understanding of the period will lie with the records of the various intelligence agencies and the investigations that took place into their involvement in assassination attempts of foreign leaders.

As for the chances of all the documents getting released, I find it highly unlikely that we will see all the documents in 2017. Unfortunately the CIA has the tendency to keep documents secret long after they are relevant or dangerous to the security situation of the United States. The CIA will probably argue that revealing some of these documents will reveal the methods and practices off the CIA which would make them exempt from the FOIA law and prevent their release, I hope whoever the president is at that time does not give into them

Side question? Why is it a big deal if there are two or more shooters?

Side question, if I may: what's to stop the CIA from deleting the really bad stuff and releasing cherry-picked documents that don't show illegal and immoral stuff like MKULTRA? As for MKULTRA, we wouldn't have ever known about that if they hadn't misfiled some documents and mistakenly didn't destroy them. So really, are we actually expecting to find anything critical of the CIA in any of these released documents?