Bethesda has said there will be another ES title. They just haven't said when.
They've also informed us that they're working on an in-house title. They just haven't said what.
That's all the official info we have.
http://www.gamesas.com/index.php?/topic/1080894-tes-v-ideas-and-suggestions-thread-%23157/ - That's the current-running thread for suggestions and ideas and discussion regarding the next game's content.
http://www.gamesas.com/index.php?/topic/1081413-official-when-and-if-we-get-tes-v-%2321/ - That's the current-running thread for speculation and information-gathering regarding when we might get an announcement.
Those links should be used and the second one, in the opening post, there is a link back to a blog post from Pete Hines last year, where he noted that Bethesda is not abandoning their Elder Scrolls franchise...