I think people can already build outposts(at least orcs can), but there hasn't been any info on what purpose they have, except for defensive purposes. Would be nice though, being able to create huge trade lines with allies.
"The flower of friendship blooms even in hell. On the sand where waves come and go, it leaves its petal as a memento. We will make it bloom again someday, The Okama Way!" - Mister 2, Bon Clay