As the King of the Underworld, even if Hades had poor relations with the rest of the pantheon, he remained a core figure in the world and Zeus's own brother.
His fall would inevitably cause turbulence throughout the world, and the gods would soon learn of the news and rush to the Netherworld.
By then, the descent of the gods would be the true crisis they had to face after killing Hades.
Chapter 202