A new teaser page
has appeared on the Diablo 3 website hinting at a possible expansion entitled "Reaper of Souls. We know that a Diablo 3 expansion is inevitable, although a potential announcement this soon was somewhat unexpected. The general consensus was that Blizzard would allow some time for the upcoming console version to develop before revealing any relevant information about the expansion. However with the PC version's decline as of late, Blizzard may be forced to make a move sooner than they would like. Still we are merely speculating about the teaser page, it is in no way a confirmation of an expansion.
More Diablo 3 information is confirmed to be revealed at the upcoming Gamescom which takes place during the end of August. Whether this applies to the console version, expansion, or simply a large content patch remains to be seen.
The teaser page includes a quote from the Book of Tyrael
which is set to be released on October First. Blizzard recently stated that some secrets would be revealed within the artbook. This information combined with whatever is announced at Gamescom should give us some concrete ideas on what the "Repear of Souls" actually is within the next couple of months.