I think Oda will show Marco fighting Queen and King at the same time, prob flying away from Queen but still getting shot at, while King keeps flying after him and trading blows. Then Marco will start to be punished, if Queen starts using Kairoseki bullets (wich we know exist here in Wano and Queen should have them), he could start damaging Marco and that fight will start to look rough.
So then some people will have to take Queen's attention. I think Sanji's Raid Suit Cape could block the Kairoseki bullets and save Marco from a deadly shot and then Sanji will start 1v1 against Queen, letting Marco fight King 1v1. I think Drake should see from down there the shit happening up there and could go help them, but won't get there right away, so Sanji will 1v1 Queen for a while, and then Drake can show up a few clashes later to help Sanji, if things start to look a bit bad.
Besides this, i'm not quite sure. If Oda is going to do something to Marco to let Sanji fight King and Drake Queen, it has to be something really important, like maybe hold the Big Mom piates or something. I also don't see Marco going up the roof, because he is not part of the new generation, he is the one that said the fight on the roof is about the new generation vs the old, Marco has no place up there, even as a support, Law should be the doctor up there, Marco the doctor here in the middle, and Chopper the doctor down there and inside the castle.