In a recent interview with TechRadar, Yoshiyuki Inoue ( Senior Engineering Planner) mentioned that the LX5 camera sales are not as good as Panasonic had hoped. One of the possible improvement for the LX5 (and D-Lux 5) replacement could be the sensor size. A new 1 inch sensor (like the new Nikon 1) was mentioned, but nothing was officially confirmed (FYI: the Leica D-Lux 5 has 1/1.63″ CCD image sensor).
The Leica D-Lux 6 is expected to be announced in 2012, probably in September during Photokina.