Every time someone asks about a new ST or SC truck, I go back to this interview.
http://www.rcnews.net/2015/12/09/int...-team-durango/
You have the popularity of the class, which is still quite low compared to buggy, and the cost of them making new molds for things like rear arms. Hell, we can't even get bodies for the truck and that doesn't need a new mold.