The issue is just last chapter. Atlas straight up tells us whoever controls the pacifistas win.
And that they can't escape if the pacifistas keep blasting them.
Both Kizaru AND Saturn are going down here.
I don't think Kizaru next chapter.
But it's not great he isn't the main villain here.
For me the problem isn't Kizaru going down this arc. Even if he isn't the main villain he could go down after a proper fight.
The problem is "the proper fight" part. The battle barely got focus and we saw 3 or 4 moves with Kizaru not even focusing on Luffy and now he's already tired. It's cool that we're seeing some new moves from him but for the first serious admiral 1vs1 fight we see in this manga the way Kizaru approached the fight is far too anticlimatic. (Akainu on Marineford and Aokiji vs Garp don't count. Oda treats battles with main characters much differently than between secondary characters even if they're serious, like Oden vs Kaido).
If he gets serious and shows better stuff, with actual focus on Luffy, the fight can still be redeemed, but that leaves the problem of Saturn, who by all means should steal the spotlight just due to his identity and role.
Even if Saturn survives this, the Pacifistas can just be destroyed or distracted by the Ancient Robot or whatever. I'm sure Oda has something in mind for that part.