Summary
TheDiabloseries is full of unique locations that make up the desolate world of Sanctuary, andDiablo 4in particular showcases this world like never before due to its open-world design. WhileDiablo 4already includes areas like the snowscapes of the Fractured Peaks, the marshes of Scosglen, and the deserts of Kehjistan, there are more locales around the series' world that future content could explore. One iconic location that a futureDiablo 4expansion could take players to is the High Heavens, but there would be some complications that might prevent Blizzard from going this route.
Diablo 4is already set to return to a fan-favorite location fromDiablo 2as the upcoming Vessel of Hatred expansion will take place in the jungleregion of Nahantuand the city of Kurast. This location is perfect for following up on the ending ofDiablo 4’s base game since Kurast has a history with Mephisto and the Prime Evil’s influence over the surrounding jungles. The finale ofDiablo 4’s main campaign already sees players head into the Realm of Hatred within the Burning Hells in the quest to prevent Lilith from absorbing Mephisto’s essence, so it would seem like a natural progression for the game to take players to the High Heavens as well.

The Pros and Cons of Adding the High Heavens to Diablo 4
Diablo 4 Could Utilize the High Heavens in an Interesting Way
The eternal conflict at the heart of theDiablofranchise’s lore pits the High Heavens, the realm of the angels, against the Burning Hells, the realm of the demons. While thiswar has spilled into Sanctuary, the realm of the humans, rarely do humans ever set foot in the High Heavens or Burning Hells, but there have been instances where the player has traveled to these realms. MostDiablogames end with players traversing the depths of the Burning Hells, but the High Heavens have only been accessible to players inDiablo 3.
As such,Diablo 4has the opportunity to expand upon the lore of the High Heavens and follow up on a hanging plot thread from the end of the main campaign. With the death of therogue angel Inariusand the Cathedral of Light targeting the player and the Horadrim as heretics, it would be interesting to see the High Heavens intervene in this conflict. Perhaps players could pursue Prava, the new head of the Cathedral of Light, into the High Heavens after she seeks their aid in eradicating the Horadrim, potentially allowing players to fight angels in addition to demons.

Adding the High Heavens to Diablo 4 Could Diminish Its Presence in Diablo 3
Although there are still a plethora of stories that could involve the High Heavens inDiablo 4, it might be best to avoid returning to the location simply to leave it as an iconic part ofDiablo 3’s identity. Humans in theDiablouniverse almost never enter the High Heavens, so having too many games where players can access that realm would remove some of the mystique around it. The first and only time players have been able to enter the High Heavens was inDiablo 3, making it a significant part of the game’s identity that would be diminished if the High Heavens were accessible inDiablo 4.
InDiablo 3, players are forced to enter the High Heavens after Diablo grows powerful enough to force his way in and attempts to corrupt the Crystal Arch, the source of the angels' power. This creates a dire situation where it becomes necessary for a human, or a nephalem in this case, to enter the High Heavens, and they do so with the help of the fallen angel Tyrael. Having a human able to enter the High Heavens inDiablo 4would undermine the seriousness ofDiablo 3’s finale and lessen thepower ofDiablo 3’s Nephalemcompared to normal humans.