I've been saying it all along in those Luffy vs threads, that Kaido vs Luffy was just an ability walk through in order to get to know G5 and that Oda did it with Kaido, because thanks to his very high blunt force resistance he could allow himself to get hit by Kaido that much.
Looks like even tho he becomes goofy, FS and all is doing just fine.
Serious Nika Luffy, which we still haven't seen, where he applies actual techniques to ggn giant would steamroll Kaido aswell. I think he might show some good stuff against Kizaru's light avatar form. GB's tree form made his durability against physical attacks skyrocket aswell.
That's to say that Kizaru is not done yet. I still think he's the main atangonist. An admiral with a logia fruit won't have 4-5 named attacks and no confirmed awakening. That's just dumb to assume.
If it really comes down to a main fight, Kizaru is my man