Eventually, Zoro will defeat Mihawk, the man who once rivaled Red-Haired Shanks. As such, Zoro will be close to Shanks' level and could even surpass him by the end of the story.
Mihawk holds the title of "World's Greatest Swordsman" and, as such, it is beyond any doubt that his swordsmanship skills are superior to those of Shanks. This was, once again, brought up in One Piece 1058 where he was specifically compared to Shanks.
Shanks is MASSIVELY stronger than Luffy. Shanks is so much of a badass that he can casually block a full power attack from Akainu. We've seen Shanks block a full power Conquerers haki infused strike from Whitebeard.
Luffy is close to Shanks in terms of power and it is only after their fight that he will officially be able to call himself stronger than Shanks.
Shanks has clashed against Kaido when the latter tried to reach Marineford. It is very likely that Shanks would be able to injure Kaido in this battle.
Pitted Against The Navy's Strongest
In this case, it is safe to say that with further mastery of Gear 5, to negate its drawbacks, as well as a bit more proficiency in his use of Conqueror's Haki-infused attacks, Luffy should be able to defeat the two Admirals by the end of the story.
Shanks is possibly the strongest Conqueror's Haki user alive in One Piece. He paralyzed Admiral Ryokugyu, one of the strongest Marines in the entire world, with his Conqueror's Haki from miles away.
It is evident that the only person capable of surpassing Roger is Luffy. Even though Luffy still has a lot to achieve, he is the only person who can transform the entire world.
Currently it should be Shanks. Shanks is narratively depicted to be as strong as old Whitebeard. Garp is at best at that level, both being previous Roger's rivals. But that should also mean that prime Garp was stronger than prime (current) Shanks, since Shanks, as hyped as fans want him to be, isn't Roger level.
Shanks possesses the ability to use Kenbunshoku Haki, as revealed in his vivre card and has almost unrivalled mastery over it. He is known for being the Killer of Observation Haki as he is able to stop people from being able to use it as seen from Kidd.
It is a known fact that Kaido has lost to his fellow Yonko and the Navy a combined 7 times and been captured a total of 18 times. While Kaido might be the strongest in terms of raw strength, there are definitely those who can beat him a fight. Write for Us!
Shanks is probably way above Zoro`s level. Of all the characters still alive in One Piece, Dracule Mihawk is undoubtedly the strongest swordsman in the world. After all, he holds the title. Vista was the commander of the fifth division of Whitebeard`s Pirates and was considered the best swordsman in Whitebeard`s crew.
Sir Crocodile was the main antagonist of the Alabasta arc of the series and the first Shichibukai that Luffy took down. Crocodile is easily one of the most difficult fights that Luffy has ever fought as he lost to him twice. In fact, Luffy would've died both the times had luck not been on his side.
While using Gear 5th, Luffy is able to extend his elasticity to inanimate objects. Luffy's devil fruit awakening allowed him to beat Kaido, who was considered the "Strongest Creature in the World." In his Gear 5th form, there are not many One Piece characters who can defeat him.
Lucci is a member of CP9, a secret agent of the World Government. This group employs deadly martial arts alongside Devil-Fruit powers in a combination that nearly kills all of the Straw Hat Crew. While Luffy manages to fight off Lucci, he would have died without the help of Nico Robin and Usopp.
Fans were introduced to this ability through Charlotte Katakuri during the Whole Cake Island arc. According to Bege, Katakuri had trained his Observation Haki to a level where it allowed him to see slightly into the future.
The only way to hit Kizaru is by using Haki or using powerful air vibrations like what Apoo Scratchman did to land a blow on him.
Coby is one of the most talented characters in the series. Just two years prior, he was merely a kid with below-average strength. Now, however, he is a marine rear-admiral and a pretty strong one as that. He's strong, but not strong enough to be Luffy's match.