There are plenty of options, right? Kyle or John would be the obvious choice, since we’re supposed to lose an Earth born GL. Then there’s faceless thousands in the Corps, or even some of the lesser used, but still named Corps members. How could they possibly totally shock us here?
By having John use his Indigo Ring to channel the Black, and then cement himself as John “The Planet Killer” Stewart, and blowing Mogo straight to hell with a big construct gun.
Rest in Peace, Lantern Mogo. You will be dearly missed.