This space is for additional DLC's you would add if you could to Skyrim or any ES game. You can also put anything you would add or change to an existing DLC.

I'll start. A DLC I would add would be for Cyrodiil. This DLC would add a small explorable area of Cyrodiil, and maybe even add some new quests and items and enemies. I would also add to the Dragonborn DLC that you could become a were-bear.

Keep an eye on Skyblivion, I think that's been making good progress lately.

I would create a DLC that explores the ancient Atmora, that would make for a very interesting experience. I'm pretty sure the devs behind Skyblivion are making a mod for that as well.

I would make a DLC that tells the story of lus, the true animal god. Having you enter his dungeon while he is asking if akatosh is entering because of your dragon blood.

I do need to say that I'm a big fan of the Skyblivion DLC because i love both games and nothing can be better than combining the two of them.

I would make a DLC that would allow you to explore all of Nirn. Needless to say, it would be enormous.

I think a DLC with deeper insight into the falmer (maybe curing them), more dwarven stuff, and some new spells would be cool.

Ruvgein
Beyond Skyrim:Bruma is Skyrim's 4th DLC, I don't care what anyone else says! But no, the beyond Skyrim team is quite awesome with everything they're trying to make. If I had to make a brand new thing, though, it would be on the Nordic Gods. Skyrim had a big lore cop-out when they made all the Nords use the Imperial Pantheon. So I'd want a DLC to explore what changed to make them so Imperialized, and how the bandits still worship the Old Gods, and that's part of why they've been kicked from the cities.

Especially considering that the Nordic pantheon was essentially confirmed to be at least partially real during the main quest. Shor's bones, you even get to walk across Shor's bridge of bones! They fleshed out some parts of the Nordic mythology while somehow making it feel incongruous with the rest of the game's portrayal of religion. I was so disappointed by that!

Hahdremro

Especially considering that the Nordic pantheon was essentially confirmed to be at least partially real during the main quest. Shor's bones, you even get to walk across Shor's bridge of bones! They fleshed out some parts of the Nordic mythology while somehow making it feel incongruous with the rest of the game's portrayal of religion. I was so disappointed by that!

They did flesh out Nordic Kyne with the trials and other little things, but the rest of the time it seems they just went "Kyne is what they call Kynareth, so it's like the same thing". 

Falkreath isn't dedicated to Orkey, the College of Winterhold doesn't once say Jhunal's name, and I would pay money to see a group of people gathered around a shrine of Alduin, praying that the World-Eater isn't hungry today and he'll keep the dragons away from their farms.

Seeing how Creation Club is being handled now shows that there is a clear need to provide worthwhile content for the existing games Skyrim and Fallout 4. Otherwise, when the next sandbox title comes out with Creation Club attached people are going to be pretty upset with the microtransactions for content they might as well wait for the mod version of.
Now that they have moved on and are working on their next title; Bethesda should allow the partnered developers and content creators to make New ‘Canon’ Expansion sized content for their games. 
Rather than releasing tiny bit sized like armor and weapons individually. Create an expansion that includes those kinds of items that can be obtained through quests and exploration. 
That kind of content is a far more tempting purchase than what is the equivalent of “Horse Armor”.

Since it is going to be awhile before we get another single player Elder Scrolls game why not continue the story of the Dragonborn? Skyrim was recently re-released on next gen consoles so expansion sized content would tap into that market who want more to do after they complete Skyrim and its existing DLCs. I see no reason why we cannot expand upon many existing storylines set up in Skyrim as well as add new ones. Especially now that Community made mods are doing just that.

Starting with this thread I am proposing ideas for Quest and Landmass based expansion content. 
So Idea one.

Elder Scrolls V Skyrim: Wrothgar

Wrothgar is a region in the North-Eastern Mountains of High Rock bordering on Skyrim.
The province was featured in a DLC for the Elder Scrolls Online, which takes place about 1000 years before the events of Skyrim (2011). 
It’s History that we know of is detailed here: http://elderscrolls.wikia.com/wiki/Wrothgar

-What is happening in the Fourth Era?

What happens to Nova Orsinium during the fourth era has been left largely unknown, but it is revealed that the grand city of Orsinium was besieged by the Bretons and Redguards of the Iliac Bay. The Sack of Orsinium had not only consisted of the Orcish Militia, but the defense was conjoined with the Seventh Legion and the Fifteenth Legion. In the end, Nova Orsinium was besieged, and many Orcish citizens migrated to the east, in the province of Skyrim. Before this exchange, the only establish Orcish settlements in Skyrim was the legendary stronghold of Cradlecrush, which was destroyed a long time ago. Another was the Grand Chieftain of Yashnag gro-Yazgu which was razed by Hakkvild Yashnag-Slayer, the Jarl of Falkreath during the Interregnum. When the Orsimer moved into Skyrim, they established several strongholds including Dushnikh Yal in the Reach and Largashbur in the Rift. The Orcs were still considered citizens of the Empire but continued to live isolated lives from the city-folk of Skyrim.

-Why Wrothgar?
1. It is a province larger than Solstheim meaning it could offer near twice the amount of content of the Dragonborn DLC.

2. Much of the world-building and Art design has already been done and gives the Devs something to work with when establishing Wrothgar in the Fourth Era.

3. Wrothgar has unique enemies and fauna specific to that Province, making it stand out more from the previous add-ons
 

4. Wrothgar creates twists on things that we have seen before in Skyrim. Introducing the player to unique branches of the Dragon Cult, Reachmen, Dwarven ruins, Giants, etc. AND explores Orc culture along with their relationship to Skyrim.

Why not have a faction of Orcs, Reachmen, and Nords who turned to Dragon Worship and went to establish themselves in Wrothgar?
 

5. Wrothgar could also provide more build-up of the Altmeri Dominion conflict and their reach across Tamriel. As well as the Empires position there.

6. it could expand on the types of armors and weapons that players a can find and craft. So if you have the Orcish smithing perk you can now craft other types of Orc gear. Maybe introduce a new Dragoncult look players can use?

To Summarize: Skyrim is about the Nords and explores their culture, so Wrothgar provides familiar content to Skyrim as well as delivering something new, making it the perfect location for the Dragonborn to go to next.

paarthurnax

Keep an eye on Skyblivion, I think that's been making good progress lately.

What's Skyblivion? I can't check the link because of my school's proxy.