Everyone is well aware that Dante's Inferno ended with us hearing the silent laugh of Lucifer just before Dante enters Purgatory...
Here's what I think will happen:
Sequel 1: Dante's Purgatorio
Lucifer, as the snake that used to be Dante's tapestry, slithers through Mt. Purgatory, trying to reach the Garden of Eden, and his presence sullies the very landscape. Dante's task is to relieve each Steppe of Mt. Purgatory of Lucifer's influence. However, the Archangels mistaken Dante as the one who affected Mt. Purgatory, so he's also trying to prove his innocence.
The Final Battle would take place in the Garden of Eden.
Sequel 2: Dante's Paradiso
Dante is permitted to enter Paradise to see Beatrice and his deceased family, but Lucifer, who somehow escapes defeat in the Garden of Eden, begins his war with Heaven. As Dante battles Lucifer's army in the Nine Spheres of Heaven, he is aided by the angel hierarchy in each one.
Gameplay wise, unlike Inferno where you gain Unholy Magic as you progress, you have to buy them with Souls like you did with Holy Magic. All Holy Magic you gain is through progression.
In the last Heavenly Sphere, Dante fights Lucifer alone again, and this time, he (Dante) forces him (Lucifer) back into the Inferno, and seal it off completely from Purgatory and Paradise. Dante is then allowed to remain with his family in Heaven.
Opinions and critique are accepted.