We're told that Zeiss will announce the next in the Otus line, an 85mm f/1.4 for Photokina this September. We're also told that it's possible an Otus 35mm f/1.4 could also be announced, although that isn't confirmed. If the 35 isn't announced at Photokina, expect it some time in 2015.
What comes after those two lenses is unknown. Although we have heard that a pair of tilt-shift lenses are in the works, as well as an Otus zoom lens.