The story can also be improved upon and the lore of the Plaga can be expanded as well. They can add more variety to Separate Ways. I hope a Revelations 3 happens as well but with this new RE engine era, it will be harder for them to bring back main characters who haven't been reimagined into the engine yet like Rebecca, so well see.
Separate Ways is a quite cool additional campaign and really adds to the story but you know what would be really cool to see? A bonus mini campaign with Krauser, have it start with the first meeting of Krauser and Wesker, and how Krauser is assigned to go to the pueblo and enter the Los Iluminados cult, receives the plaga for his arm and finally add the mission on U.S soil where Krauser kidnaps Ashley, but not without having to confront a team of U.S. Marshals along the way.