I'm a Yasuo player. He's by far the most played champion across my accounts. But It's time for the shield to go.
Yasuo used to need the shield for trades early, having the lowest base HP for a melee champ in league it was needed to not get stomped by every champion in top.
But now with the new runes he got some nice sustain in Taste of blood and Ravenous hunter.
Now onto the New Conqueror,
>Attacks or spells that deal damage to an enemy champion grant 3-15 Adaptive Force (based on level) for 3s >(8s for melee). Stacks up to 5 times. When fully stacked, heal for 10% of damage dealt to champions and >convert 10% of that damage to True Damage."
Remember Fervor of Battle? And how Yasuo was able to stack it really fast?
This new one will stack faster, and give him even more healing.
Tl;Dr, It think that with the new Conqueror Yasuo will have too much safety with healing from runes, So remove his shield.