Why Ash vs Evil Dead Season 4 Isn't Happening

screenrant.com:

Ash vs Evil Dead was canceled before season 4. The Evil Dead sequel gave viewers a look into the later life of horror icon Ash Williams, famously played by Bruce Campbell. By transitioning the franchise into a TV series, the creators were able to expand the Evil Dead mythos across three seasons.

Campbell and Evil Dead series creator Sam Raimi didn’t hesitate at the opportunity to bring back Ash Williams. This time around, they ramped up the comedic side along with an ample amount of blood and gratuitous gore. Ash vs Evil Dead, which aired on Starz from October 2015 until April 2018, excelled at showing Ash in a new light, especially with his new trusty sidekicks, Pablo (Ray Santiago) and Kelly (Dana DeLorenzo).

Related: Bruce Campbell On Why A Freddy Vs Jason Vs Ash Crossover Film Wouldn't Work

Each season of Ash vs Evil Dead presented an increasingly new level of danger. As the stakes grew higher, so did Ash’s responsibilities. Not only did Ash have to deal with being a father to a recently discovered teenage daughter, Brandy (Arielle Carver O'Neill), but he also had to face more than the typical threat of Deadites. The fate of the universe was in Ash's hands with the threat of Kandar the Destroyer, a sixty-foot-tall demon creature. In Ash vs Evil Dead season 3's final showdown, Ash seemed to sacrifice himself to save the world but he was revealed to be saved by an unknown group. When he woke up, years had gone by, but before viewers could get answers, Ash vs Evil Dead was canceled. 

Before the premiere of Ash vs Evil Dead season 3, the previously released seasons were streamed on Netflix. They were a hit with subscribers and the cast and crew had hoped that it would have a positive effect on the new season.