Turns out Zeus (Russell Crowe) isn't dead. However, he is furious after 

Thor (Chris Hemsworth) tricks him with his weapon, the Thunderbolt. 

He claims the world is too focused on superheroes and complains that no one believes in God as much as they used to.

 He decides he must defeat the god Thor, who plays the superhero. 

Thor's rivalry with Hercules dates back to 1965's Journey Into Mystery Annual #1, 

and their first encounter is detailed in the miniseries Thor: Blood Oath (2005). 

It will be interesting to see what path Hercules takes in the MCU. As the mighty Thor,

 Jane Foster (Natalie Portman) succumbs to cancer at the end of Thor: Love and Thunder

But she may not be gone forever. In a post-credits scene, Heimdall greets Jane at the gates of Valhalla,

asking her to enter if she wishes. Jane smiles, perhaps a little unsure, and the scene goes black before Jane can respond.