Oh I don't wonder, I know that there is a world where Kizaru could defect. I don't think it will happen but its completely possible.
Oda is not really writing "this" right now. He is just showing that Kizaru is doing things a little bit unwillingly, but he is still doing it. As of now, there is no clue indicating that Kizaru is about to defect (it could arrive, but we don't have that right now) and the chances for him to do so passed with him attacking Vegapunk. So Kizaru will most likely not defect.
For Oda to prepare Kizaru to defect right now, you would need to see a real hesitation in him.
- Lucci do intend to kill Zoro, the later is just too strong.
- There are no mysteries concerning Lucci.
- And Lucci didn't interacted in a specific way with the strawhats besides Egghead. And at was in a bad way not in a friendly way.
I'm sorry, but there are very few chances - not to say none - for Lucci to turn his back on the gov now. At least with Kizaru, we had reasons to believe so, but there are none with Lucci.
I did never believe that Kizaru was ever going to turn his back on the WG. In fact, the moment the admiral voiced his concern for Bonney, Kuma and Vegapunk, while trying to hurt them, was the point, when I knew that Luffy would in the end face Kizaru as his main opponent. Because in the past, Luffy always did face the villain, who was either responsible for his new crew mate’s suffering or was the main obstacle for his crew mate’s freedom.
The reason for this thinking is the following: With Kizaru going against his friends, he is going to be the moral reprehensible opposite to the arc’s still veiled protagonist (Lucci), who I have always told has a twin-like counterpart in Shaka (family). This would mean that Lucci is in the same position with his mission inevitably requiring him to go against his family/friends – just like Kizaru’s. Isn’t this coincidence odd to you?
In the past Kizaru and Lucci sacrificed people for their greater goal (Like Robin or Iceberg). Those people were more or less strangers or acquaintance to them. Now, things are different and in the current situation with both characters needing to face the decision of either hurting the people they love (friends/family) or to go against the WG and face the consequences of betraying them.
One of them will go against his friends/family and remain in the WG's service. The other will choose his friends/family and will sacrafice himself.
(I think, I will start reading Marineford in the near future, since we have the same buildup here on Egghead. 😉 All that we are missing now is the character of Ace.)