With the news a while ago of Hearthfire trademarked by Bethesda, speculation has begun to run rampant on the next DLC installment.
Bethesda, or I should say it's parent company Zenimax, has filed for trademarks on a variety of Skyrim related phrases like Dragonborn, Fus Ro Dah and the most recent DLC name: Dawnguard. Their filing for Dawnguard is what began the speculation for that DLC and many well thought out theories and rumors, especially when combined with a few leaks, turned out to give us a pretty good amount of information on at least the subject of Dawnguard. (Dawnguard spoiler: Even my own theory of Snow Elf Vampire turned out to play a part).
Their latest filing was for "Hearthfire". Players may know that Hearthfire is the name of a month in Skyrim that corresponds with our own September. There is also a book that can be found in game called "Palla, book one" that focuses on Necromancy and the holiday Tales and Tallow. This has lead to quite a bit of speculation that the DLC will involve the undead. Some are calling it the zombie DLC due to the popularity of zombies these day, but in skyrim lingo it would involve Draugr, Skeletons, and other nasties that a necromancer could conjure up or control.
That has been pure conjecture based upon the in-game book. Fans may remember that Todd Howard, head of Bethesda, stated that Skryim DLC will come in many forms. They won't all be large expansions, some may just be small little things added for a lower price here and there. This could be one of those instances.
A theory by one fan (reddit user: derptemp6698 who has been correct about a couple other advanced pieces of info on previous DLC's from other games) is that the features of Hearthfire will allow a player to build their own home from the ground up. Though this ability would be lost on some PC players due to the ability to add mods, Bethesda's XBox exclusive deal may be enough to entice them into creating such content for console users. Plus, if done right, would still be of interest to most PC users when eventually released to them.
Let's not forget the gamejam Bethesda attended last year, where they unleashed their developers to create new code for Skyrim that could benefit the game, no matter how crazy. Some ideas have already made it into the game from updates: combat from horseback and crossbows to name a couple. Could Hearthfire bring about a few more of these? One of the demos during gamejam showed seasonal climate change - which may make sense with a fall themed DLC rolling out. Plus, there is still always the fan favorite, spears, that seems to always make it's way into rumors through fan desire more than fact.
Either way, players should expect the DLC to be released on XBox first, with at least 30 days of exclusivity. This deal with microsoft has been known since Skyrim first launched, so I never understood the fan shock and outrage when it happened for Dawnguard. I would also expect them to get Dawnguard out for the PS3 before going into the next DLC phase, though continuing issues with getting the game bug-free on PS3 has caused constant delays for that platform.
Perhaps we will hear some official information soon. If the content was going to focus on "fall" time period for Skyrim, you would think they would try to launch it during our own fall. Not to mention if the DLC was going to focus on more than home-building and dive further into Necromancy, getting this content out on our before Halloween would be a smart move. So far though, Bethesda's only response when asked about Hearthfire is "No Comment".
UPDATE 8/27: I have started to see some articles popping up talking about this DLC as fact. As of this date, everything I talked about in this article is still rumor, even the name. Though some of it is based on reliable sources, it's still just speculation and no OFFICIAL announcements have been made by Bethesda.
Also, on a related note: update 1.7 is now out for Europe and Australia.
UPDATE: 9/7: Correction for name of in game Tome referenced, pointed out by commenter Falcon Stormvoice. And links added: