We know that Deep Silver is the sole owner of the Sacred franchise, so I'm going to go out on a limb and speculate that this teaser website for Sacred World that they casually mentioned in a Tweet and Facebook post earlier today is for an upcoming MMO continuation of the action RPG series. Add to that the meta description "Official site for Sacred World. Game information, news, screenshots, videos and more. Learn all about the world of Sacred." and I think you'll arrive at the same conclusion that I have.
But is it a traditional massively multiplayer RPG? Or maybe a more co-op focused, open-world action RPG in the same vein as its predecessors? Or perhaps it's some sort of mobile and/or social game that brings the series in an entirely different direction? I guess we'll just have to wait until August 7th to find out for sure.