Yasuo would actually be really balanced in this current state if there were just a few changes.

There are two paths Yasuo can take here.

Damage-Support, where his damage isn't overwhelming, but he can still contribute to a teamfight with his ultimate and still wreak havoc in the backline, sort of like Pyke, but with more damage than CC, and more utility instead of stealth.

Assassin-Carry, where his damage is the level it's at right now, but his utility is heavily nerfed.

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I know that Yasuo was nerfed, but the current iteration of Conquerer benefits Yasuo much more than it does other skirmishers due to the healing and adaptive damage it provides. It just changed Yasuo from someone who kills Squishies really fast and Tanks fast into someone who kills Tanks fairly fast and absolutely DELETES squishies. There are several reasons for this, like his high mobility, AA + Q + AA damage thanks to his passive's crit multiplier, his shield... the list goes on. Give Yasuo the Latest Irelia treatment by making him more specialized, instead of neutralizing the entire ranged roster with 1 ability, W, while taking on the entire melee roster with 1 ability, Q.

With that in mind, I'm looking at nerfs that make him more specialized, and some nerfs and buffs to make his early game weaker, to give him a defined niche late game.

Damage-Support changes:

Yasuo's Crit damage is 150% instead of 160%. His Q cooldown isn't reduced by attack speed, but has a fixed cooldown that scales and isn't reduced by CDR. His Ult now keeps enemies knocked up for an additional .25 seconds at Rank 3, but is reduced by .25 seconds at Rank 1. His E can be recast on any minion, and the 5 second cap is removed. His E cooldown is changed to 5/4.5/4/3.5/3 seconds. His W now moves forward 600 units, but lasts only for 1 second.

These changes aim to reduce the sheer damage Yasuo can dish out, and instead focus on making sure he can maintain relevant as a niche support, or build as a fighter instead of a straight up assassin that still heals more than fighters do. I honestly do not like this form of Yasuo, but I suppose it's a way Yasuo could be kept down low in terms of sheer power.

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Assassin-Carry changes:

These changes aim to make it much more punishing to make mistakes for Yasuo.

Reworked abilities:

E: He keeps all current damage, and his E can now scale past 100% bonus damage up to 250% bonus damage, but the damage is only increased by 10% per dash, until the 6th dash, which increases the bonus damage by 200% instead of 10%.

This change aims to benefit Yasuo players who can cleverly use their E as both a skillshot dodger, and also an engage tool, instead of just using E to get in and out. You can either increase your damage of your E by dashing through all the minions in the wave, or you can leave some unmarked as an escape at the expense of your damage.

W: Either: Windwall now lasts for 0.5/0.55/0.6/0.65/0.75 seconds instead of 4 seconds, and using it will remove 20 Flow. The CD is reduced by 4 seconds at all ranks. It no longer passes through Yasuo's hitbox at the beginning of the cast, instead beginning directly in front of Yasuo's hitbox. It will only drift forward 20 units instead of 50 units.

This change is intended to make Yasuo have to rely solely on reactionary casting at the expense of the free shield, punishing him if he casts it incorrectly. It also forces him to actually build up some resource before using it, and prevents his W from going through his hitbox.

Or: Windwall now has a 0.5/0.45/0.4/0.35/0.3 second delay and no longer passes through Yasuo's hitbox at the beginning of the cast. It lasts 2 seconds instead of 4, and drifts forward 300 units instead of 50.

This change is intended to make Yasuo unable to rely solely on reactionary casting, and makes his windwall drift forward to allow actual positioning changes instead of just walking back and forth between the windwall at the expense of duration.

Optional changes: His R no longer sets the knockup duration to 1 second, but has a faster animation of 0.5 seconds, allowing him to deal damage at the expense of gaining free CC. This change aims to reduce the impact Yasuo has in teamfights, but improves his ability to deal a lot of damage to a single target.

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With these changes as a start, I think Yasuo would be much less painful to play against, while also opening up new avenues for Yasuo mains to explore. Of course, these changes might make him undertuned, but Riot can choose to buff number values instead of adding new mechanics. The goal of these changes is to make Yasuo less unbearable to play against while making him less of an all-around perfect champion that's overbearing when overpowered, but underwhelming when heavily nerfed (those few precious hours right after 8.11). Similar to Irelia, making Yasuo easier to balance while making him nicer to play against is potentially a win-win-win situation that has the potential to benefit both Yasuo mains AND Yasuo haters, as well as the balance team.