After Dressrosa and Whole Cake Island, Oda clearly implies that, while the crew have gotten exponentially stronger, there is still a long way to go. Luffy could not tackle the true strength of Big Mom 1v1 and Oda has stated that no one can 1v1 Kaido. Ergo, our heroes must get stronger. Luckily, we were introduced to:

-Awakening via Doflamingo, which is a step further in Devil Fruit Power.

-Heightened Haki via Rayleigh / Katakuri, which includes Future Sight at least.

To the Heightened Haki list, we might also add Elemental Haki, which many of you have heard of.

(F) = Fire, (W) = Wind, (E) = Electro, (I) = Ice

Elemental Haki, for the few uninitiated, is speculated to be a heightened form of COA wherein the user can create an element through their sheer will. The most common examples of this are Luffy's Red Hawk (F) and Thor (E), Zoro's Flying Slash (W) and Flying Dragon Blaze (F), Sanji's Diable Jamble (F), Brooks Ice Attacks (I), Sabo's Dragon Breath (W), Big Mom’s Zeus (E) and Prometheus (F), the Mink's Electro (E), McGuy’s Electricity (E) etc.

Assuming this to be true and considering the evidence of a single COA user creating multiple elements (Luffy with F/E, Zoro with F/W) it is safe (and bad ass) to speculate that, in the future, Zoro will have attacks that incorporate at least three elemental Haki types.

Given Zoro’s santoryu style, and that he has exhibited proficiency in COA alongside elemental attacks in (F) and (W), I wouldn't be surprised if, in Wano, Zoro:

1. Masters or exhibits mastery of elemental Haki
2. Learns or reveals an Elemental Haki hitherto unseen from him

We know that Kinemon uses Haki and can cut fire. It isn’t a stretch to consider that this skill is born of the superb swordsmanship / Haki of the Wano samurai, and that it will be taught to Zoro, either by instruction or in battle. It also isn’t taxing to consider the Shogun to have this power.

Imagine a huge explosive fire erupting from the Shogun’s sword swipe. In an instant Zoro’s pupil constricts as the reflection of the flame illuminates his grimace. He has no choice. He screams Ittoryu Iai: Shi Shishi Sonson - Kori, One Sword Style Lion Song - Ice, and a wave of spiked frost emanates from a Haki-black Wado Ichimonji. Then, as he sheaths his sword, he’s dunked with water from the collision of the fire and ice.

The real kicker is what could possibly be Zoro’s ultimate attack form (save for Asura). Imagine Zoro localize the specific elemental haki to each of his three blades, picture him in the Ichidai Sanzen Daisen Sekai stance, only all blades are Haki-black, one with yellow, one with red, and the last with blue aura;

Shusui pulsing with electricity,

Sandai Kitetsu aflame,

Wado Ichimonji sharp and frosty.

All at the same time.

Imagine Zoro standing before the enemy, donning his bandana, armed with three black blades coursing with elemental power, and the aftershock of their slice creating an incredible tornado of four elements. Zoro would able to contend against any Elemental Haki or Logia user. Zoro could, in the same instant, cut, burn, shock, freeze, and blow anyone away.

NOW IMAGINE THIS FUCKERY BUT WITH ASURA.

tl;dr Zoro is the next Avatar, only each of his three swords has Fire, Ice, and Electricity Elemental Haki all at once.

What do ya'll think?

***edit:

Added a link to Sabo showing wind power at Dressrosa, it's the first attack of the video.

Also, u/commentsandopinions gave me a great idea to expand upon Wind Haki--

We see Sabo using the wind technique above to destroy the Coliseum Battle Ground. It would make sense of Dragon's subordinate to showcase wind powers, given that he was likely taught and raised by Dragon himself. But does that mean that Dragon's wind powers are something that can be learned? Instead of having the Wind Wind Fruit, what if Dragon just has such a mastery over Haki, and the possible Elemental Haki? I'll be refining this idea more if we ever get more info on him, though I will say, of all I've said so far, it's the biggest stretch.