Makers of Horizon Zero: Dawn currently looks for game programmers who preferably have experience with multiplayer. The game they’re working on? Guerrilla wants them to work on an “epic open world game.”
While Guerrilla still hasn’t announced what game they are working on exactly, the description of the job listing implies that it is a Horizon Zero: Dawn sequel. The listing notes that this new open world game will have ranged and melee weapon combat and traversal mechanics. No doubt, as you can guess, these traits are all applicable to the game above in question.
If it is a Horizon Zero: Dawn sequel, then it is entirely plausible that the new title is introducing multiplayer features. After all, why would Guerrilla be looking for someone with experience in that field if they weren’t?