The way the Daedra were implemented in Oblivion svcked big time, they were nothing but your typical brutish enemy, in Morrowind they were more sophisticated and you could even interact a little with them. Exploring their shrines was really creepy too
In Morrowind, there were really only a few Daedra you could interact with in any way other than combat, and these were, with a few exceptions, quest related, the ones you could talk to didn't even have much to say and, in at least one instance (The one in he Maar Gan shrine.) saying what you were supposed to would lead to a fight to the death. Really, in that regard, little has changed.
Though I do miss the Daedric ruins. The single statue out in the wilderness setup of Daedric shrines in Oblivion just didn't have the same effect of the ominous, evil looking ruins filled with dangerous Daedra and cultists. The only shrine that even tried to do something similar was the one to Mehrunes Dagon, and it was probably only like that because it was supposed to be the Mythic Dawns base of operations, and even then, it still used the generic cave tileset with a few parts from fort ruins added in and some Mythic Dawn banners hung around it. You'd think with it being a dungeon that provides a fairly major turning point in the main quest, they could have done something a little more unique with it.
But I think we can safely assume that Daedra will be in Skyrim, they've been a stable of the series since they were created, after all. But I doubt they'll have a major appearance in the main quest, being as Bethesda already told that story. Most likely, they'll be done in a way that's more like Morrowind. They'll be there and they'll be part of the world, but not the main enemy you must face, some side quests might deal with Daedra, and I expect to see Daedric shrine quests, but for the main quest, it seems like dragons are going to be our main enemy after all.
I don't want Daedric armor to look like its counterpart in Morrowind, though, or like the Oblivion version, I want an original design that hasn't appeared in past games before, same with other armors. I liked the Daedric armor in both Morrowind and Oblivion, but there's no reason Bethesda shouldn't do something different for Skyrim, as long as it looks good and captures the demonic look I've come to expect from Daedric, I'll be pleased. If I want to see the Daedric armor from Morrowind or Oblivion, I can play either game, or if I want to see it recreated in Skyrim's graphics, I can wait for a mod to do so, just as Morrowind's Daedric armor was recreated in an Oblivion mod.
One thing related to Daedra I do hope returns in Skyrim, though, is Daedric dungeons like in Morrowind, because as I've said above, the statues out in the wilderness just seemed rather boring in comparison. The Daedric shrines don't necessarily have to look the same as the ones in Morrowind, as those ones were designed with Morrowind in mind, they might look a little out of place in Skyrim, though to be fair, looking out of place might not be a bad thing for Daedric shrines, because it would make them feel more alien, still, it would seem a little strange to see ruins like Morrowind's in Skyrim.