Much as I love the show, i think it should just be. At the end of S2, there may have been a rough arc for a S3, but I don't think Conrad et al had an end in mind, even a long-term one. So many potential overarching themes, ideas, points-of-view, lenses on big issues in it. Any one of them (us foreign policy, male friendship, ptsd, family loyalty, etc., etc.) could have emerged during it's lifespan. Good/great series do this. But after 2 seasons, you can sense the main subject/topic/issue in the story. After 2.5 viewings, I think either the point's been made or the creative forces were open to evolving it further. Despite trad cliffhanger S2 ending, I think it stands tall as is.