The issue with opening the JFK files is that it has only been 58 years since the incident. Those directly involved in the murder alive could kill informants who are still alive.
No the only reason to cover it up is to cover the governament ass die to direct, or indirect involvement. Most witnesses are dead or in their 80’s. Seriously doubt they are worth the time and effort to take out.
The USG places information protection orders sometimes to 75+ years as some groups will kill up to three generations after the fact. This happened in the 1990s with honor killings from WWII in Bosnia. As to age of those involved, 80 years young does not affect murder cases. The US has arrested and extradited 95 year old Nazis back to Germany for War crimes. I’m more interested in those that were involved as to how they gained from this murder; what groups, agencies or corporate entities may have benefited; or if their decedents gained because of these actions (poisonous tree benefits). The fallout could still be politically and economically devastating depending the level of involvement and the gain from the JFK death.