Well, the thing about this is that now JoJo will get 9 episodes to air in 2016, finishing the Phantom Blood Arc, and DBZ Kai proper will also end on the 17th. I now believe the New Year's Eve-il Marathon will be a JoJo Marathon of the first 9 episodes extended to 4:30 AM.
So now Gundam IBO S1 ends December 10th, so now what on the 17th? I had originally thought Children Who Chase Lost Voices might get a midnight rerun on Christmas Eve, but I now believe its fate may actually be 1 AM on December 17th, as Hunter x Hunter, Shippuden, One Piece, and One-Punch Man all take a 3-week break. I'm calling either DBZ Kai or Hunter x Hunter marathon on Christmas Eve and JoJo Phantom Blood marathon on New Year's Eve-il!
We have seen now that they have the capability to expand Toonami to 4:30 for a special event, and the Phantom Blood arc of JoJo would indeed fit the bill, but the question is: is this expansion to 4:30 AM permanent for 2017, and if so, what would a 9-show Toonami look like? Even with DBZ Kai and/or Gundam IBO getting more seasons, we've still got room for 2-3 new shows, and I believe one of them will be Mob Psycho 100!