@Rambles
The past is about to repeat itself. In Enies Lobby, after the Buster Call was triggered, Cipher Pol 9 was defeated, and left to die by the WG. After escaping, Spandam blamed them for the failure and destruction of Enies Lobby, and Marines were sent after CP9. While eventually they rejoined the WG and joined CP0 during the Time Skip, for a period, CP9 was wanted by the WG/Marines.
Well, where are we now? Kaku is down. Lucci is going to be down soon since he's fighting Zoro. What happened to CP9 agents who failed or were defeated? They were either arrested, or killed. So, is it fair to assume that CP0 works the same way?
If Lucci and Kaku fail here, guess what Saturn is going to do?
That's right; leave them to get Buster Called like the "insects" they are.
I COMPLETELY FORGOT the government just arrested or killed CP9 who failed. Even if Saturn doesn't order their arrest/murder, once he sees Stussy is a traitor, and Lucci and Kaku are down, he'll leave them to die.
Just like before, Lucci and Kaku will get Buster Called by the World Government, but, this time, they won't rejoin them.
Then, they get teleported to Wano Act 4 to finally witness the reveal of Pluton, since that's how CP9 was introduced, searching for Pluton.
I'm not sure if this will lead to Lucci becoming an ally, but it's a definite pathway. I could see Luffy telling Zoro to save Lucci and Kaku from the Buster Call, leaving Lucci in a Alabasta Smoker situation.
Smoker and Luffy were captured, nearly died together, then Luffy had Zoro save Smoker, making Smoker finally accept that Luffy wasn't his real enemy. Lucci won't become an ally this arc, IMO, but something will stop him from being an enemy and open up that pathway.