Well, if somehow he vows never to pillage again, that would be enough for me, lol. Now regarding Umbar, I'm not sure how the writers will handle that, as indeed piracy is a way of life after so many years. Who knows, maybe our King will find a way to, at least close the gap between the two peoples. Maybe by force, maybe by trade, maybe by politics. I don't think the former, as Aragorn doesn't strike me as the guy to enforce an Iron Rule.
Like, I wouldn't mind Jajax seeing the wrong of his ways. But indeed for the whole Umbar to stop pillaging and raiding some other measures will be required.
P..S: @MoL don't you dare pull a George R.R Martin on us and kill Jajax, I'll be beyond devastated!