I believe that Momonosuke is gonna get captured since he is a pretty important character and we need him to be at the battle because he is the next one to become the daimyo. So because of that they are gonna go after Kanjuro and Momo to Onigashima to start the battle. I also think that not all of the ships were destroyed since if that's the case they would have a pretty hard time-fighting Kaido. I do also believe that Zoro is gonna be a big deal in this fight since he has Emna that cut Kaido in the past and I also believe he is gonna get Ame no Habakiri and Shusui because they both are known to have cut dragons like Shusui has cut a legit dragon in the past so yeah.
So with all of this, I still think its gonna be a tough battle but the only whey I can see Luffy being any use is to awaken a new form so that's gonna be gear 6th I think. The reason I think this is the case is that the first time Luffy and Kaido fought, Luffy lost big time and ever since that fight he has been training this new technique that allows him to attack an opponent from the inside out.
As you say I would also like Blackbeard to be there since we need to see him again and it's so obvious that he is gonna the strongest devil fruits of each type. Also, Sword is probably gonna be there as well since Drake is a part of that and I really like the idea of Sword, Blackbeard and the marines standing over Kaido's body in like a three-way standoff.
So yeah that was my thoughts