Didio talks about the 5G plans for Superman here (around 53 minutes in):
-Bendis was involved with Rucka and Zdarsky in plotting out the “last” JL story which wouldn’t kill the old guard off but would give them new roles that made them step aside for the younger generation
-Superman’s powers were fading because as an “energy battery” he couldn’t store as much energy anymore, the Authority were a team he built to circumvent this problem
-Jon and Damian were going to be foes, but akin to Professor X/Magneto where there’s still respect and a bond between the two. Jon and Luke/Jace were not going to be close because Luke/Jace didn’t trust how close to Damian Jon seemed
-Big endgame story for 5G, built up over 5 years, was going to be Clark busting Bruce out of prison where he had been put for the death of Bane, and Jon/Damian/the new Batman would be going after those two. Final showdown between the old guard and the new seems like that would have put a cap on 5G