I would like to see a more comprehensive tutorial that teaches survivors and killers everything they need to know before they go online. What I mean by this is a tutorial on how to use every perk effectively and a practice mode against bots. This tutorial can vary from beginner to advanced and it gets more detailed the more time you spend practising. I always thought it would be a good idea to explain perks like 'Borrowed Time' to new players or teach specific builds that you can use.
Also, a story mode would be cool. I always imagined it being a single player experience with AI teammates that you'd have to work with and objectives that you'd have to complete like 'Escape the match with everyone alive.' It could be like you have to help Laurie Strode escape from Michael Myers on Haddonfield. Your objective would be to make sure she survives the trial. If she dies, you fail or something like that.