We have now got confirmation that DragonBall Kai will indeed stop at the end of the Cell saga and will not continue on towards the Majin Buu arcs. It was speculated some time back that this would happen since the new anime Toriko would be taking DB Kai’s time slot once the Cell saga was finished.
Takeshi Kusao, the Japanese voice actor for Trunks, has stated there are only four episodes of DragonBall Kai left but he hopes the also remake the Majin Buu story. The Cell saga ends with episode 98 on March 27th 2011. You can view a copy of the scan where the interview was provided below.
So there you have it, DB Kai will be over very shortly. FUNimation has already nearly finished dubbing the Android/Cell saga of DragonBall Z Kai, with new episodes of the Android saga airing every Wednesday and Thursday on Nicktoons. So, for now stay tuned to the latest DBZ Kai episodes and hope they will return and remake the Majin Buu saga as well sometime in the future.
November 2012 Update: Dragon Ball Kai Buu Saga On Its Way/