From Sakazuki’s words, it seems as if he was waiting for Law vs BB to end so he could easily pick off any pirates injured post battle.
With Law and Bepo sustaining severe injuries from the BBP, they would be easy game for any strong marine. This is where I think Koby will come into play. As we saw, Koby is an excellent swimmer. With his powerful CoA and CoO, he could easily spot and apprehend Bepo along with an injured Law.
I think that due to him being a Sword member, Koby will try to form an alliance with Law to bring down Teach. They both have a vested interest in defeating him as Teach likely captured the heart pirates while the BBP took Garp. Given their common backstory with the Rocky Port incident, I could easily see Koby and Law teaming up to fight the BBP. Especially if Akainu is hesitant to make any marine efforts against Teach.
