The 406x is listed on this page -
http://www.h3.dion.ne.jp/~c-yellow/2...Japan_4WD.html - as a 4wd, only thing shown though is a b4 body painted in what looks to be Satoshi Maezumis' colors. I've seen references elsewere and always refered to as a 4wd buggy.
They cant possibly drop the development of a TRF offroad shaft drive, it's just not like tamiya. They've classically always been pro shaft drive. If they think it's still worth developing the TB Evo platform when the 415 is doing so well, then i'm sure they'll release a shaft offroad TRF car..