Redo the pain arc so that Sasuke gets brought into Pain's influence via one of the Akatsuki rings he should have from Orochimaru or Itachi.
Sasuke initially attacking the village and prioritizing finding the elders while going along with the order to suss out where Naruto is.
After losing to Tsunade, Sasuke getting caught up in almighty push, only survives due to Sakura directing Katsuyu to protect him.
Regains consciousness to witness Naruto defeated by deva Pain and impaled, his body moves on its own and stands up to Pain.
Naruto sees Pain crush Sasuke and impale him.
Sasuke dying in Sakura's arms, with his last words being to give his eyes to Naruto to finish his business with the elders and avenge the Uchiha.
Sakura preparing the eyes while Naruto finishes things with Pain.
Sasuke awkwardly getting revived without eyes but saying he talked to Itachi in purgatory and he's just gonna go ahead and get the EMS now and he's still holding Naruto to cleaning up the village he intends to run as hokage and he won't give him long to handle it himself.
Sasuke reconvening back with Obito where he is treated with hashirama cells while recovering with newly transplanted eyes.
Some bullshit happens and there's now 3 pairs of rinnegan for the war.