I know everyone and their mothers and ME have said this before, but they really should've let Michael kill God.
Can you imagine having prevented the apocalypse multiple times since the OG apocalypse and then coming back full circle with Michael ending the world. The first time was because his Father commanded it and he loved Him. And now it's bcs an all-consuming grief of losing the only person he truly loved and who truly loved him.
The last shot of the show would be a dead planet (you can see the moon in pieces in the sky), the dead bodies of the winchesters, God dead with these MASSIVE wings scorched into the ground, Michael standing in the midst of it all with his eyes glowing red