I would like to see an interactive epilogue. A lot of games will have pre-designed endings. Based on various criteria, if you fulfill them you get a specific (good, evil, neutral, etc) ending. What if the ending is treated another chapter where the hero or villain presence and actions throughout the story has changed things, and the PC gets to go in-game to these locations, to visit the people there, to experience it all in-game? To make the ending have a more lasting impact on the player, the ending is not just something to unlock once and that is it. For example if the PC is a villain and he revisits a location, the people there would run away from him.