What if... at the end of ch 880...
"Hello? I'm sorry, Luffy…" Nami stared up at Big Mom riding the giant wave that would soon be crashing down on the Sunny. Tears began to blur her vision and fear struck her heart. "I think we might be done for…"
…
Inside the sweets factory on Cacao Island, Sanji was busy mixing the ingredients for the filling of the wedding cake that would save his friends from Big Mom. It had to be perfect. Anything less would risk them being obliterated. Suddenly a cold shock of fear struck his heart… That was strange. He wasn't afraid of anything at the moment. Then it hit him: Nami-san!
The cook immediately abandoned his station and made his way towards the factory exit. "Where are you going, Mr. Husband?" One of Whole Cake Island's finest chefs ran after him. Pudding took her eyes off of her chocolate to see what was going on. Chiffon noticed the commotion as well.
"I need to go!" Sanji looked from Pudding to Chiffon. "Nami-san is in danger!"
"Sanji-san… How can you be sure? Aren't they all in danger at the moment?" Pudding approached her 'husband'. She didn't like how concerned he was about that cat burglar.
"Something is wrong, I just know it… I can feel it."
"But Black Leg," Chiffon joined the small group. "If she really is in danger now, how are you going to get to her in time?"
Sanji frowned. Lola's twin sister had a point. "Pudding-chan, I need to borrow the magic carpet," he decided. Not waiting for a response, he grabbed Rabiyan and took off towards the door again.
"Sanji-san, wait!" Pudding cried desperately. He ignored her plea and continued on his way. Then a more sinister voice called to him, "Stop right there or I'll shoot, Sanji-!" He still didn't turn around. "…-san. "
"I know you won't do it, Pudding-chan," Sanji waved away the threat, not bothering to look back at her. He unraveled Rabiyan. "I need to hurry and save Nami-san!" There was a click, then a bang. Not even a second later, the cook felt an object penetrate his back and rip out through his chest. The projectile continued its journey until it lodged into the factory door in front of him. … A bullet? Looking down, he saw his white groom's outfit rapidly turning red. Well, fuck.
Collapsing to the ground, Sanji became vaguely aware of the scene his former bride had caused. Chefs were running away in fear. Chiffon-chan was yelling in shock. Pudding-chan had run up to him, screaming, "Kyaa! Sanji-san! Are you okay?!" Then her voice transformed again, "You deserved it, you bastard! No one else can have you, Sanji…" Tears poured out of all three eyes and she added, "…-san. "
Soon his hearing began to fade and Pudding's split personality conversation became a soft muffle. Thank God! I needed some peace from her. Sanji closed his eyelids. They felt so heavy. His breath was shallow. In his last moments, his thoughts went to the crew. Nami-san… Luffy… Everyone… I'm sorry. You'll have to find another cook. My journey ends here.