What Phasmophobia has in store for future updates is not yet known but, we can make some educated guesses. There is currently an open Trello Board that tracks community ideas and responses to updates to the game. Here we can see what ideas seem to be gaining a lot of traction.
On the docket, we've got to let ghost players do more. When you're killed in Phasmophobia you become a ghost, however, there's not much you can do in this form. You can interact with some objects, follow around the other players and yell at the ghost, but you can't interact with the other players or gather evidence. In the future, there might be more options for ghosts to assist living players or perhaps even turn against the living but we'll have to see.
There's also a chance that Kinetic will allow players to select maps to play on rather than subjecting them to random chance. This could theoretically give players a better quality of life, but also undermine the horror to some extent. If players only start playing on the same maps they're comfortable with over and over again, it removes the aspect of discomfort and surprise by allowing players to master a specific area. While that's great for shooters and RPGs it isn't exactly an asset in horror games.
Since Phasmophobia is still in early access there will likely be a lot of content updates in the future, we'll just have to see what Kinetic puts forth.