I still believe it’ll be Sakazuki. Scopper or whoever the “come” dude was will probably just be an ally to send the straw hats to the fourth poneglyph afterwards.
But personally, after seeing Imus reaction to Luffy escaping, I cant imagine Imus just going to wait for Luffy to come to him. Plus with the plots of the Grand Fleet members being introduced in Egghead to Elbaf, it feels like odas setting up a big war between SHs and the marines just like egghead alluded to at the beginning of the arc.