Has any show with a similar theme survived more than one season? Jericho made it two seasons, but those weren't full seasons.
What I mean by the theme is something set in a reality very similar, but vastly different than ours. Present day Earth but something like a nuke or nukes going off. I wonder if this just strains the credibility too much for the typical Network TV viewer. It's not a reality based show (like your typical crime drama), yet it's not a flat-out Science Fiction show, either.
24 lasted 8 seasons with multiple nuclear detonations on American soil, multiple assassination attempts on US Presidents, resume regimes, coup attempts, the White House invaded and President taken hostage, biological terror attacks on US soil, etc...