I just read that Jeb is working on more Stone variants for 1.8... So, since the world generation will be updated yet again, we will delay adding new outposts to the frontier until then so that they will have fresh 1.8 terrain with new stone.
The new block is Granite and when Jeb was asked about if that means having to go generate new land to get it he stated something along the lines of making it craft-able.