Roronoa Zoro is the Combatant of the Strawhat Pirates and also their second strongest member after their Captain, Monkey D. Puffy in One Piece. At Wano, the Strawhat Pirates have allied with the Heart Pirates among others to take down Yonko Kaido, and Kurozumi Orochi. Zoro's strength has always been of enormous use to the Strawhat Pirates everywhere they go, and Wano Country is likely to be no different.
Just like all the other Strawhats, Zoro has gotten progressively stronger by crushing enemies wherever he's been to. As such, there is no doubt that he'll get significantly more powerful at Wano. Here are 5 powers that Zoro will gain there, and 5 that he won't.
10 Will Gain: Full Control On Enma
Towards the end of Wano Country Act 2, Roronoa Zoro was asked to return Shusui to Wano Country since it was considered to be an irreplaceable asset. In place of Shusui, Zoro was given one of the swords of Kozuki Oden, called Enma.
This sword has a special property of drawing out insane amounts of Ryuuou from the user's body, therefore, not everyone can wield it. As of now, Roronoa Zoro hasn't displayed full mastery over this blade, but it is just a matter of time before he does so, and in the process, gets stronger.
9 Won't Gain: Saijo o Wazamono Grade Sword
Saijo o Wazamono Grade swords are 13 blades of the highest quality in the world of One Piece. So far, only three of these weapons have been revealed, two of which are wielded by Dracule Mihawk and Yonko Whitebeard. Although Zoro uses three powerful swords, none of them are of the highest quality.
Right now, Zoro possesses two O Wazamono grade swords in Enma and Wado Ichimonji, and one Wazamono grade sword called Sandai Kitetsu. Having recently gained Enma, there's no chance for Zoro to gain a blade of higher quality in the story before Wano Country arc concludes.
8 Will Gain: Ryuuou
Introduced at Wano Country, Ryuuou is the ability to emit Busoshoku Haki via the user's body or weapon from over a distance. This ability is something that's common to the Samurai of Wano. Over the course of time that Luffy spent at Wano Country, he managed to learn this technique as well.
To get even stronger, Zoro will certainly gain the ability as well. After taking over Enma, Zoro's control over his Haki is likely to have improved manifold and as such, there's no reason to believe that he cannot emit Haki as every other strong Samurai does at Wano Country.
7 Won't Gain: Future Sight
Future Sight is an advanced level of Observation Haki used by those who have trained this power to the absolute extreme. Once awakened, it grants the user the overpowered ability to look into the future for a couple of seconds. Although Zoro's Observation Haki is decent, it is not nearly as refined as Luffy's, or Sanji's.
Zoro has been shown to rely excessively on Armament Haki, and therefore, the Haki zone where he'll excel the most is likely going to be Armament Haki, instead of Observation Haki.
6 Will Gain: Asura
First manifested by Roronoa Zoro during the fan-favorite Enies Lobby arc, the Asura is a power that multiplies Zoro's body three-fold. When used, Zoro gains two more heads, and six more arms and legs. As such, instead of three, Zoro gains the ability to use Kyuutoryu, or Nine-Sword Style. Although this ability has been shown to be incredibly powerful, Zoro has never used it after the time-skip which is strange, to say the least.
Since Wano Country is likely where Zoro will be fighting against King the Wildfire of the Beasts Pirates, it goes without saying that he will need to rely on the power of Demon Asura once again.
5 Won't Gain: Advanced Ryuuou
Among the many new concepts that were introduced at Wano Country is the concept of Ryuuou. Described simply as a form of Armament Haki that can be channeled over a distance, Ryuuou is an ability that Zoro will most likely gain at Wano Country. However, its Advanced form is a mind-blowing power that lets a person channel their Haki directly into the body of others and destroy then from the inside out.
So far, Luffy and Rayleigh have displayed the usage of this ability. Although Zoro is impressive when it comes to Armament Haki, it is too early for him to learn Advanced Ryuuou.
4 Will Gain: Nidai Kitetsu
Said to be one of the cursed swords, the Nidai Kitetsu is an incredibly powerful blade belonging to the Kitetsu family. Right now, Zoro already has a blade from its kind called the Sandai Kitetsu, which is also the weakest of all the three Kitetsu blades. Sandai Kitetsu was crafted by Tenguyama Hitetsu, but interestingly, a stronger blade crafted by his ancestor Kotetsu, known as Nidai Kitetsu is at Wano Country as well.
With no owner right now, it is almost like an open invitation for Zoro to take the blade in his possession. Although he hasn't done it yet, Zoro will likely have taken this blade by the end of the Wano Country arc.
3 Won't Gain: The Voice of All Things
The Voice of All Things is a special ability in the world of One Piece that allows a select few users to hear the voices of people and even objects. As of now, this ability is shown to have been wielded by Gol D. Roger, Luffy, Oden and his son Momonosuke.
Using its powers, Roger was able to 'hear' the Poneglyphs without being able to read them, displaying the immense power of this ability. Zoro may be strong, but this is an ability that is certainly not suited for him. Among the Strawhat Pirates, Luffy is likely going to be the only person with this power at his disposal.
2 Will Gain: Conqueror's Haki
Conqueror's Haki is a special Haki form that cannot be awakened, and instead, a person is either born with it. Although it is said to be an ability gifted to those with the qualities of a King, Conqueror's Haki is not an uncommon ability in the New World. All the Captains, and some of the right-hand men, such as Katakuri and Rayleigh, have previously displayed Conqueror's Haki in their arsenal of powers.
As such, Zoro is certainly going to be one of its users in due time. At Wano Country, Zoro is likely going to fight his toughest enemy to date and it'll be interesting if he manages to unlock this mysterious power there.
1 Won't Gain: Devil Fruit
Being a pirate who fights using the infamous three-sword style and Haki, Zoro is certainly someone who doesn't need the powers of a Devil Fruit. Over the years, Zoro has displayed the potential to surpass even the strongest of swordsmen and as such, he has a high ceiling that he hasn't touched yet.
With lots of room for improvement, it seems bizarre to believe that Zoro will, at any point, eat a Devil Fruit in One Piece, simply because he has no need for it and can get stronger by fulfilling his potential in time.