Agree with the rest, but why would Mihawk help Im? For starters, Mihawk is now an enemy of the WG, and also Mihawk isn’t a bad guy
It's just a Guess, based on few Hints:
1. He should be Zoro's Final FIght
2. Dracule means both "Son of Dragon" & "The Devil"
3. He is only Character in entire One Piece who have Eyes drawn like Im-Sama's
4. His Personality seems fitting for someone with Nobility
5. Oda didn't drew him "Poor" as a Kid even though he appears to be a Lonely Man
6. His Original Epithet was gonna be "Clairvoyant" which kinda sounds like Im-Sama
I also can't really imagine Mihawk as a Bad Guy, but it's a still a possibility & Oda could use such Plot Twist to give Mihawk his Final Arc Role. After all, Mihawk is just like Shanks & Dragon, a Character who appeared extremely Early in Story but haven't done anything & only reserved for Ending.
But you can remove him, since i agree it's a weak guess.
What i truly believe is that Final Arc is about Luffy + Shanks + Dragon vs Im-Sama + Teach + Akainu