First of all, I'm aware that Bethesda probably wants to separate Fallout and the Elder Scrolls in terms of gameplay, thus not using every feature in both titles. I believe they especially like to avoid imitating things from Fallout: New Vegas. Nonetheless, I half expected Skyrim to have a kind of hardcoe Mode as FO:NV did, especially since it would be easy to separate from the ordinary gameplay, and also because I know a whole lot of people who are fans of the franchise would like some old features returned - things that may make the game more difficult in some ways, but they'd have their positive impact as well.
In this so-called hardcoe mode, the most obvious difference could be the same as in FO:NV - mandatory sleeping and eating. Skyrim already has food items separated from ingredients, only now food is relatively useless compared to potions. Sleeping is also less useful than in previous games, seeing as you don't need to sleep in order to level up. And if your style of playing includes not hurrying level-up, the resting bonus for skill gain is obsolete as well. Additionally, as attributes regenerate on their own anyway, it's generally pointless to sleep to regain attributes as well, since you could just as well use "Wait" to achieve that. Hence, it'd be pretty logical, in my opinion, to have an option to utilize a mode where it's necessary to sleep, if only to give inns some purpose, and increase immersion.
Another feature could return some things from Morrowind regarding questing - mainly no "essential" characters, and no weightless and sticky quest items. Whenever a character vital for completing a major quest dies, you could just recieve a warning that you've eliminated your chance of completing a quest, suggesting that either you should load the game from a previous point or carry on playing, knowing you can't complete said quest. As for quest items, I liked the fact that in Morrowind, you could sometimes sell a quest item instead of using it to complete the quest, either on purpose or by accident. These sold items should then probably stay in the inventory of the merchant you sold it to, in order to not ruin your chances for completion for good. This way, you could also sell or store items related to quests you have no intention of ever completing.
In addition, also as a reflection from FO:NV, all other weightless items could probably have weight, including arrows and gold, making it necessary to stash gold someplace whenever you have too much. To some it may sound like busywork, but I personally would like it, hence it would make a fine addition to this theoretical "hardcoe Mode".
Another thing I had in mind - not related to "hardcoe Mode" - was some sort of reputation system. It would once again be pretty much imitated from FO:NV, but it could have some integration with the Fame/Infamy system from Oblivion, the abscence of which I was a little surprised about in Skyrim. Of course, in Oblivion this feature was fairly pointless, since its only purpose seemed to be whether or not you may receive blessings from shrines, and maybe some other minor things I may have missed myself.
The way I see it, Fame should be a value of no alignment, it would just represent the character's renown throughout the game world, not reputation itself. However, the higher your fame, the more your reputation would shift whenever appropriate. Fame would increase with questing, clearing dungeons, acquiring or selling artifacts, and otherwise proceeding in the game world. Infamy would be an "evil" value, increasing with any type of crime and Daedric quests, perhaps, as well as questing for shady factions. The difference between Fame and Infamy would then be the character's "positive" fame value.
Expanding on the "Reputation" concept, since Skyrim already has a wide variety of factions, including Holds themselves in addition to guilds and unjoinable groups, it would make sense to have some sort of dynamic reputation among these factions. I found the disposition system in Skyrim to be fairly shallow, and I would like to see it taken further, in terms of wider ranges of dispositions and non-direct effects on a faction's disposition towards the player character.
Finally, I think it's a little bit sad and also a little weird that since Daggerfall, there hasn't been a possibility to create a background and other unique values for the character. I think one of the best things about Daggerfall was the option to add advantages and disadvantages to your character, that would affect how fast said character would improve throughout the game. I don't see any reason why it couldn't be possible to utilize this in Skyrim, in addition to the playable races' "solid" characteristics, such as Dark Elves' fire resistance, Khajiit's Night Eye, and so on. It would add so much initial depth to a character if you could designate they get diseased very easily, or can only regenerate Magicka when in the dark, or that they're specifically talented in fighting the Undead. And this basic system could be expanded so much further from where it was back with Daggerfall.
That should be all I had in mind. While I am aware that similar threads must exist regarding previous games as well as Skyrim, I'd like to discuss these and other ideas both in theory and as possibilities for DLC or future games.