Imo, we have 2 major arcs before the Final War, Elbaf and Laugh Tale.
- I "can" see Elbaf being heavily Vegapunk/Kuma focused. Maybe Kizaru is the villain (Luffy needing to master FS, a different issue than Kaido).
- Laugh Tale could be BB in the end, sort of paralleling WB's speech (that Blackbeard isn't the man to challenge the WG, Luffy is). You get that final clash of ideals before Luffy is PK. Either this or BB survives into the Final war (but i dont think hes the final antagonist).
- The the final war is primarily against Akainu and Im, a two part major fight war sequence where Luffy uses One Piece to "liberate" the world.
- However, in a coda to the series, Shanks is the last antagonist (along with Mihawk), maybe even at God Valley, for an ulterior motive we don't understand yet. This way, the series ends just as it begins, with the oldest One Piece character outside of Luffy. Shanks could be the emotional close to this series, not the most epic. The person that ties together the hat being returned (if it even carries the same meaning by then), the person that allows Usopp to fully close the chapter with his father, and finally, the person potentially leads to Zoro achieving his dream.
I do think these are the 5 major players left for Luffy. Even here, you can also guess Zoro's opponents in the end:
- Kizaru/Kuma (rebuilt)
- Blackbeard/Shiryu
- Akainu/Fujitora/
- Im/Monk Gorosei
- Shanks/Mihawk
I know not everyone agrees with this, but I'm totally down for this fight order if this is what remains (no I personally do not like Yonko more than Admirals or vice versa). Anyway, we'll see what happens. We should know what is coming next by the end of the year hopefully. I don't expect to be right at all, just something I think might go down this way