Carrot and Yamato were the last new additions I could see working, as of now I only really see Vivi joining as the honorary Straw Hat turned official 11th member. Loki could be a great ally, but I don't think he'll join the crew. He could work just fine independently, making strides for his goals then being crucial in the final war without joining Luffy's crew. Maybe Yamato hops on for the final voyage (the last section of it anyways) like Oden, but things could easily work with it just being a case of Yamato and Momonosuke aiding Luffy's crew when they need help rather than an official joining (like Carrot being leader of Zou). Plus, as far as dynamics go, Jimbei already has some issues with being shown to be an essential addition to the crew, Yamato or Carrot would just worsen such issues, Vivi is a pre-established ally with dynamics with more than half of the crew already and the rest could benefit from meeting with the most important friend the crew had pre-timeskip (they're going to learn about the X mark and a reunion seems not too far off regardless). Plus, with Vivi being targeted and in hiding, the issue of her having a nation to rule is removed since she can't do that until the leader of the World Government is dealt with hence she can easily become a member until the aftermath of the final war.
Bonney and Kuma are cool, but with the prospect of Lilith treating Kuma, and Kuma's ties to the Revolutionary Army, I wouldn't be surprised if Bonney and the crew part ways this arc. She did and is doing fine in the Law role of being a Worst Gen ally over a few arcs, but I don't think she'll officially join. She could, but why stall that when it could've been done post-Egghead?