I am pretty sure we will get a Manhattan POV's DClock issue right before the finale, in which we will see his plans/motivations behind all the changes he made to the DC Universe, while also answering the many questions that have been brought up in this thread
But the one I wanna see answered the most (besides the whole Oz deal) is the Superman split-up
It hasnt been touched upon since reborn happened, I wanna see the endgame behind it