I had Kuzan trying to stop Teach from finding the One Piece, but I've realized Pluton makes way more sense.
What is the catalyst for Aokiji as a character, as far as we know? Ohara. What was Ohara centered on? Pluton. How was Aokiji introduced? As someone concerned over Robin's ability to resurrect Pluton.
Kuzan is going to turn on Teach to try to stop him from claiming Pluton. After, it is possible he joins the Straw Hats, but, I think it's more likely Kuzan joins whatever Marine force ends up splitering off from the WG.
Oda left Yamato behind because she was too strong, it'd be wild to add an Admiral so soon after.
How do you feel about Lilith joining, now that she's getting Straw Hats gags with Brook?
I'm still waiting for Vegapunk's flashback to make a final guess. Most Nakama flashbacks have A LOT of the same beats in them. I'm way higher on Lilith for Nakama than Bonney right now. The Revs have Commanders for each sea, but not for the Grand Line. I think that will be Bonney's job; the Grandline Revolutionary Commander.
Interesting theory on Kuzan, although I mostly saw him being loyal to BBP until the very end, then doing the switcheroo.
Arguably, if Sanji does get his time to shine and somehow overpowers Kizaru, then admirals would seem like below M3 level and an ex admiral (without a leg and an arm btw) might seem plausible, but there are too many "what ifs" and recent Aokiji anime hype.
As for Vegapunks I'm a little meh for them joining tbh, I don't really like the concept of many Vegapunks, it will be weird to me how they can survive w/o Stella even though they all kinda share the same brain, so I'd be more content if the whole bunch joins Revos (due to VP past with Dragon), and SHP go their separate ways. As you said, we still miss a flashback for them, only for the old man, and both VP and Kuma are on the verge of death at the moment.
I still love the fact that Caribou wants to join BBP, although I was under impression that Caribou already works for them when he had his "I gotta tell this person" thoughts!
Pluton plot seems to be interesting, too, Caribou knows that Want isn't protected well and nothing stops BB from dropping there. I would love SHP to go to Elbaf, but it might be the case that the giant plot is resolved via sailing together with th giants? And if Wano is in trouble, will Luffy go back?