Sorry, warning that this is a longish post:
To be honest, I've never understood the fan acceptance that Blackbeard is going to fight and kill Shanks and Mihawk and Shanks' crew. There are a lot of painted red flags that point to Shanks being way more dangerous than he let's on, especially being Luffy's ultimate goal outside of PK:
- Luffy and Shanks' promise. I'm not even talking about the promise in Chapter 1. I'm talking about what that promise means now. When you see Luffy talk about surpassing Shanks, it's always on a violent manner. He talks about taking down all the Yonko. "As long as Shanks isn't first" he's stated. Conversely you have Shanks who just looks straight up menacing when he talks about Luffy, especially the last time we see him.
- Then you have the weird shit Shanks has been up to with the Gorosei. Without even touching on why that's just plainly fucking weird and VERY OOC for Shanks. Oda has made the reader likely believe that Shanks is talking about Blackbeard to the Gorosei. Except we know Shanks hates BB and yet Oda left it as a cliffhanger. It begs the question: was it really about Blackbeard?
- Shanks also has 10 individual Members currently. If you believe that Mihawk may ally with Shanks, that's 11, the same number as Luffy's if Yamato joins, and the same number as Blackbeard and his 10 titanic captains.
- The pure Yakuza references Shanks has (which I won't go into too much detail, there are way too many), including his bounty and his title (he does not go by Captain, he goes by "Kashira" or Boss. Shanks is never referred to as Captain in the manga).
Idk, I've always had the mindset that OP's relative climax would just be very ordered/neat or extremely chaotic.
Basically the neat version is that BB is the final obstacle before One Piece, but One Piece isn't the final goal of the series, taking down the WG seems to be. What they do with One Piece and the knowledge from Laugh Tale/Void Century is supposed to lead them to the climax/final arc. Shanks is the tail end of this war by some unknown motive.
Or, chaotically, I can see Akainu and Im going down first in a nasty war, then I can see a 1v1v1 between the Strawhats, Blackbeard and RHP's for some ultimate goal the series hasn't revealed yet. This doesn't have to happen cleanly. For example, Wano's war is a pretty solid example of "chaotic". Some fights are laid out for sure, but the way they go down and how has been very random the entire raid. Numbers fall randomly. The F6 fell over 10 chapters at different times. Jack fell in between with Peros. Then Hawkins. Now seemingly it will be Queen (or maybe not who knows). Ther are still more Numbers and Apoo. CP-0 is still a factor. It's just a lot.