While I like this, and had an Oden is alive tinfoil thoughts of my own, I dont see how is this possible, he did survive the boiling, but he got a bullet in the head from Kaido at the end of the chapter....
Only if someone with a resurrecting DF arises in Wano I guess, or if possibly Oden himself ate that kind of a DF while traveling with Roger.
Or if Toki met someone with a similar DF to her own but that can travel back to the past, and after Odens execution and sending everyone to the future, her and that possible person traveled back before his execution, and brought him to the future, but then Oden decided to be this mysterious vigilante until someone like Luffy and SHs show up.
But then the past would be changed and Kaido and co. would know about that? Or they wouldnt if something like that happened just recently?
Or Oden was possibly sent to the future right from the boiling pot when Kaido shot him, possibly surviving the lethal bullet to the head Thanks to his overwhelmingly strong CoC, and Kaido didnt notice cuz they just thought that Oden completely dissolved in Oden stew?