I was thinking how people are upset at Remake as they feel it deviates too much from og. The creators have said that it will remain true to the original but maybe they weren’t referring to the ideas but to the core themes of og. Seeing Sephiroth introduced so early in FF7R, the whispers, different worlds etc. It got me thinking about what Sephiroth said at the Temple of the Ancients. He said “It’s simple. Once the Planet is hurt, it gathers Spirit Energy to heal the injury. The amount of energy gathered depends on the size of the injury… What would happen if there was an injury that threatened the very life of the Planet? Think how much energy would be gathered! Ha ha ha. And at the center of that injury, will be me. All that boundless energy will be mine. By merging with all the energy of the Planet, I will become a new life form, a new existence.Melding with the Planet… I will cease to exist as I am now… Only to be reborn as a ‘God’ to rule over every soul.” Remember he is in-between alive/dead as he has not be absorbed by the lifestream. The planet uses that to heal itself. If he casts Meteor he kills two birds with one stone. He kills people and mortally wounds the planet. When the planet goes to heal itself he will absorb the life energy. The worlds merging benefits him as maybe it takes two planets worth of life energy to become a god.
I think what you described would be a very interesting endgame for this story. He’s succeeded in getting rid of fate in the first installment so now the way meteor happens in the original might not happen the same way. Maybe he’ll succeed. Maybe his plan is bigger than this though since this seems very much a multiversal story. Wild idea but if he can exist between different dimensions, maybe the power of the world is the same, but him doing a cataclysmic event in multiple versions of the planet is going to stretch it’s power thin and then he’ll get what he finally wanted. I think if we see him in Zack’s timeline in rebirth then I think this idea might be a possibility.