Guerrilla Games are the developer for Horizon Zero Dawn and they appear to be working on another open world character action game that sounds in similar vein to Horizon Zero Dawn, their first open world action RPG. While it is too early to speculate their next project, it won’t be surprising to see them continue with the Horizon Zero Dawn IP after it ended up being a major success worldwide.
There are a ton of job listings on the official Guerrilla Games website and skimming through them confirms that their next project might be an open world game. Their job listing for a senior quest designer requires a dedicated developer that will help to create “ground-breaking, innovative gameplay experiences that immerse the player in the story.”
They are also looking for a combat designer for taking “character action combat mechanics for the genre to a new level.”
It took Guerrilla Games around 5 years to work on and release Horizon Zero Dawn so if we go by the same time frame, it is not surprising to see if the game ends up being released for the PS5. That said, it is also very likely that this is not the only project that they have currently in production so they might have other things to show down the line.