If Luffy is going to become Pirate King, then he has to surpass everyone else the same way Roger did in his time.
I'll use this as reference to share some thoughts on the original point.
I think there are two ways of making Luffy stand above all of them: the more literal way is for him to beat each one individually, or have him beat the other man standing by the end of the Yonkou conflict, which we all assume to be Blackbeard. Perhaps a poor analogy, but you don't have to beat all the contestants in an elimination bracket to be crowned the best competitor in the event. With that being said, I do take Luffy's words into consideration, but there are some conflicting thoughts when it comes the defeat of all Yonkous, and they're mostly related to timeframes. I'm not trying to go all armchair mangaka, but I have a hard time imagining how Oda is going to tie all the loose ends in a reasonable number of years, and still include four Yonkou fights later on, which deserve proper attention.
I guess the key here is Linlin, and what happens to her in Wano.
I'm inclined to think she's going to come back for one last round in this arc, get fleshed out a little bit more and get defeated by Luffy. She's been relevant for two straight arcs, and that's like 6 years, which is an insane amount. We've had part of her backstory, met her crew, saw her turf, stolen her poneglyph. What's left for her other than seeing her go all out against Luffy?
I guess some people suggest she might take part in Elbaf, which is the land most related to her, and it is, but I've always assumed that Shanks and Blackbeard come after Wano, so having her add another element of chaos to the next development just feels so distasteful to me. Wano had a lot of problems with how big the cast was... are we just going for another round of that? What's the point? She's been around for years now.
Some other people seem to think she'll retreat to WCI and Luffy will defeat her there, because that's what he said he'd do. Well, I guess that's also an option, but Luffy doesn't go around liberating islands. He just doesn't give a shit about the backstories. He helps friends and takes out the villains along the way. Who'd ask him for help? Linlin's own children? She needs to do something worthy of going back there, and it's scary to think how long it'd take to resolve that. It'd be like taking two steps back when we should be moving forward.
She's probably the character I'm most interested in right now. It feels like there's a lot of possibilities, and seeing what happens to her is what dictates the likelihood of every other route.
