Cavill never fully explained his departure from Netflix's The Witcher. It's easy to explain his absence by joining the DC Universe full-time, but Cavill is passionate enough about both franchises to find a way to juggle both. The prevailing theory is that Cavill no longer agreed with the direction of the show. It's an open secret that the people behind the scenes aren't the biggest fans of Andrzej Sapkowski's novels. After butting heads with the showrunners and writers, Cavill could've just given up and decided to take his talents elsewhere.
Netflix shouldn't underestimate the power of fan petitions, especially if the number keeps on growing. 200,000 fans who want to see Cavill as Geralt of Rivia is no joke.
If Netflix intends to invest in The Witcher franchise in the long term, it is in its best interest to listen to what people want. Cavill wasn't met with open arms when he first appeared as Geralt of Rivia but he embraced the role. More importantly, he speaks the "language" of the core demographic of the show. Cavill is a geek trapped in a Greek god's body.