I'm guessing it'll provide a new ending or further context like Ringed City added the Painting as a possible escape from the cycles. An entire new ending would be cool though.
Hm, after listening to a few more videos citing more accurate translations at work, our understanding of the Outer Gods seems to be a bit off
first 6 minutes of this video roughly summarize it, but he has a whole hour long one where he spoke to translators to get a more insightful look at the wording and how the Japanese community understands them
tl;dr
The Outer Gods are not "Outer" in the Lovecraftian sense strictly, they're called that because they're outside the current system of the Erdtree, but they do seem to actually be creations of the Greater Will and more importantly, they are a part of the world of Elden Ring. This is why for example, the Rot Outer God actually is sealed below the Lake of Rot, and the Formless Mother is deep beneath the Earth. This also explains why the Greater Will isn't ever referred to as an Outer God, and it makes Hyetta's dialogue via the Frenzied Flame, where the Three Fingers assert that all things, seemingly including the Frenzied Flame, were made by the Greater Will, and the Frenzied Flame wants to return everything to the oneness that existed before reality was made.
There's a lot more supporting this interpretation cited but those are the broad strokes. This does not mean they aren't still abstract or cosmic in some form. The Rot God still obviously affects the world despite being sealed away, and is also still more powerful than the Demigods are, which would include the likes of Malenia, Radahn, etc. They just aren't of the cosmos or another plane specifically like we thought they were, they are fundamental forces of the world, closer to abstract or conceptual beings than anything else. He does argue the Fairy that aided the blind swordsman in sealing the Rot God was another Outer God but I'm not entirely sure why that is, although the Fairy and it/the swordsman's power is certainly never really explained.
Interestingly, considering the Greater Will is likely not an Outer God, you have four named Outer Gods
God of Rot
Formless Mother
Frenzied Flame
Dark Moon (not specified but almost certainly an Outer God and not a "God" like Marika, the Fell God, or Placidusax' consort)
and one unnamed fifth (God the Deathbirds worship)
Miyazaki has been using this element since Dark Souls 1, 4 Lords and 1 hidden 5th (Furtive Pygmy) and again in Dark Souls 3 (4 primary Lords of Cinder and Ludleth, another Pygmy, as an obscure fifth). The DLC seems like it is going to deal with afterlife or spirit realms (makes sense as Torrent, Ranni, and Melina are spirits), possibly the Helphen, so the fifth unnamed Outer God could play a role?
So part of Miquella's plans to restore Godwyn's soul seem to have involved swallowing up the sun. I know this just means causing an eclipse, but it becomes harder and harder for me to think the Demigods are not supposed to be cosmic forces with every bit of information I learn about. Trying to cause something that blocks out the sun at all obviously means the demigods have some means of affecting celestial objects and aren't barrel level or whatever people argue.Lord Miquella, forgive me. The sun has not been swallowed. Our prayers were lacking. Your comrade remains soulless... I will never set my eyes upon it now. Your divine Haligtree.
The Land of Shadow.
A place obscured by the Erdtree.
Where the goddess Marika first set foot.
A land purged in an unsung battle.
Set ablaze by Messmer’s flame.
It was to this land that Miquella departed.
Divesting himself of his flesh, his strength, his lineage.
Of all things Golden.
And now Miquella awaits
the return of his promised Lord.
Radahn's the only straightforward raw power thing I'm aware of, Fallingstar Beast's craters might be bit feats but we don't see them land on screen, same thing with the various meteors. A lot of the rest of it is stuff mostly explained offscreen like the Black Moon being destroyed, Miquella trying to cause an eclipse, etc. I'll try and think of any other straightforward DC feats I'm just blanking on anything other than Radahn. We have a lot of meteor related spells but I'm not sure those even need to be calced (minus KE maybe?) given we can just use an assumed speed since they're summoned directly from space.@OtherGalaxy
Other than Radahn’s shit, any bit feats to look at? Don’t remember all the destructible environment or attack types in Elden Ring
No promises, but might bother at least with all angles of Radahn if I feel like it.
Lord Miquella, I still cannot make pilgrimage to the Haligtree. Our glorious sun remains held in thrall.