I still believe Carrot has a shot at joining. She already wants to set sail and unless Pedro himself comes back from the dead (and I know that some here believe that'll happen), I see her getting up to face Perospero again. She kept mentioning how Pedro's death was important and what it meant for the alliance. No reason why Oda would highlight all that unless he planned on doing something else with her later on.
She'll likely return then realise she shouldn't fight solely for revenge or something like that. I can totally see her teaming up with Chopper (who also lost against Perospero before) to redeem themselves (against this specific opponent) and help out the alliance. Carrot's already pretty close with Chopper and had a touching moment with Sanji last arc (regarding Pedro's death and how he shouldn't beat himself up over it). I can definitely see her joining the crew when most of the crew is already used to her.
As for Yamato joining, it's pretty likely at this point. All that's left is for her to meet up with the other Straw Hats (she'll probably meet Sanji soon) then head to the roof to further denounce Kaido and cut all ties with him.
Honestly, I wouldn't see it past Oda to have 2 Straw Hats join at the end of the arc even though Jimbei officially joined at the beginning of Onigashima. The Straw Hats are heading towards the endgame, makes sense that they gather all their core members now. The celebration will be even more grand after defeating Kaido since they'll also be welcoming 3 new members. I know I sound pretty optimistic but I can see it happening and whether I'm right or wrong will be clear by the end of next year (likely way sooner).