I doubt I’m the only one who thinks this. Oden was the only person to damage Kaido. He scarred him with his swords, creating an X-shaped scar.
Oden created the chink in Kaido’s armour that will be exploited to vanquish him.
Yes. Luffy will land an Advanced Armament Haki strike precisely at Kaido’s scar as the ultimate attack that brings down the Strongest Creature in the World.
The trick to beat Kaido is his scar. I found it odd but clever from Oda to highlight his scar even when he was being attacked by the 9 Scabbards.
The scar is Kaido’s achilles heel. True, Kaido WILL BE WEAKENED by the battle in Wano. But his defeat won’t be just because of that. His defeat was started by Oden, 20 years back, augmented by his loyal followers, and finished off by Luffy.