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This has always been his plan.
I've been saying this since we saw that panel. Sasuke's goal is to destroy -the world- and re-create a new physical world that works according to his idea of perfection.
This all goes back to "solutions" to "suffering."
Nagato's solution was to forcibly subject people to suffering from time to time in order to prevent them from initiating their own suffering. Essentially controlling the cycle of human suffering.
Hagoromo's solution was to give everyone magical power. Because that was a good idea.
Madara/Obito's solution was to create a fantasy world where everyone would live in peace.
Kaguya's solution is vague at this point. What she ended up doing, however, was just trying to control everyone's lives... similar to Nagato, except fun was mandatory.
Sasuke has come to the conclusion that the world as it is needs to be destroyed because it is imperfect. Since he's been gifted with the eye of a god - why not just create a whole new world using the power of the fruit?
The fruit is the power to re-cast destiny, in a sense. It is a sort of monkey's paw, the power of which wise men do not trifle with.