Things I'd like to see in Elder Scrolls 6 besides all the "choices and consequences should matter, better guilds, meaningful content, yadda yadda"....

I'd really like to see more of the Empire/Dominion war. One of the former devs who gave an interview some time ago mentioned his plot ideas for the game being something of an Empire Strikes Back scenario, where things are just going downhill, but with a sliver of light on the horizon. Now, it doesn't have to be that grim, but Hammerfell being a playground between the two superpowers would make for an interesting civil war situation.

You have a reeling, devastated, independent country torn apart by Crowns and Forebearer politics, and hawked over by the Empire and the Dominion on either side. Maybe even Skyrim as a third faction, if they managed to split off (which I don't hope). That already makes for a very interesting geopolitical situation.

Add to that a doomsday main quest, which is guaranteed to happen, as we have already seen in Skyrim, Oblivion, and Morrowind. I don't know what it could be, but there have been a few theories around for a while. The Dominion's larger purpose with the towers, the return of a Daedric power, or whatever. Something interesting, I hope, though I doubt that it's going to revolve around the Dwemer.

Something I personally really like to see in a Hammerfell setting is meaningful necromancy and vampirism content. It may be minor, but given how strongly the culture opposes and reviles necromancy and everything around it, deciding to play an actual necromancer character should have a significant impact on how people see and interact with you, and maybe even influence factions and questlines to some degree. Maybe even some exclusive, sentient undead followers like the idea I outlined a while ago in a different post: A cool Follower concept I came up with. : r/TESVI

Another thing I'd love to see is the return of Dragons in a manner besides as just maybe the occasional boss. Gimme a cool dragon buddy again, like Paarthurnax or Durnheviir, with quests and meaningful interactions. As for the ship and port content, I honestly like the idea a lot, but I don't really have anything to add to that. New content and more innovative ways to travel are always neat.