The core group at Bethesda Game Studios announced on
the studio's blog
today that they will be leaving the jagged, snowy climes of northern Tamriel behind for an unknown location. While minor updates and fixes to Skyrim will continue, the bulk of the development focus is being shifted to the next major release, which they hope will be their "biggest and best work yet."
Skyrim was in pre-production from 2006, well before the release of Fallout 3, so the team at Bethesda has spent almost seven years in its shivering sandbox. "We've invested so much of ourselves into Skyrim and will never truly say goodbye to it," the blog reads. "We loved hearing your stories, your in-game triumphs, and your suggestions."
All told, Skyrim received a similar amount of content as past Elder Scrolls games. Bethesda seems pretty set on the "two big expansions, and a handful of smaller stuff" model when it comes to TES. As for what this new project is, the most obvious answer would be Fallout 4. Then again, it could be something completely new—which we haven't seen out of Bethesda proper since the studio as it stands today was founded to work on Morrowind in 2001.
If you still pine for the Nine Holds, the modding community will likely maintain a steady flow of new Skyrim content until the heat death of the universe (or, possibly, TES 6).