Canon theories:

>Imu is Nami's father
>The Demon King in the mural is not imu, it's Teach Imu is a fraud
>The man with the burn scar is another of Joy Boy's nakama like Emett and Zuneisha, he will ultimately just give the last road Poneglyph to Luffy since he is Nika
>In the final battle, Teach will absorb Luffy's DF, but Law will perform the immortality surgery on Luffy which will revive him and Luffy will blossom his haki to a level stronger than Shanks and Roger to defeat Teach
>After Teach is defeated, all DF's will be rendered Null and disappear, leaving only haki users