Do you offer to make the game free? If your model depends on monthly fee revenue, switching to an ad-supported model or microtransactions is no trivial matter and won't happen quickly enough. Do you grant 5x experience for a month? People won't want to level up more quickly in a game they don't like enough to keep around. What's a good solution? If your favorite MMO were to make you angry enough to leave, what would keep you?