The thing with most political satire cartoons is that when they become outdated, the outdatedness hits you like a ton of bricks. It's not just for cartoons, look at sketch comedies from days yore making fun of politicians. If the politician isn't running or has some kind of current power, people just won't find the material funny anymore. One example of this was during the second season of Saturday Night Live where Dan Akroyd kept on doing his Nixon impersonations despite the fact that Carter was in office at the time. Watergate passed, Nixon resigned, show's over. Yet, Lorne Michaels and a few of the other SNL crew loved Akroyd's impersonations so much that they had him do it on and on for the rest of the season despite the audience being fed up. Had Nixon still been in office and the whole country giving him hell over Watergate, the material would've been a lot funnier because it would've been easier to relate.
This is why I'm starting to think about American Dad's future on FOX. It's a lot easier for the show to have its bearings due to Bush's War On Terror and his negative reputation with the rest of the american people. But after he leaves office and his successor takes the helm, how is the show going to work? Sure, it can parody the new successor's role in office but will it leave that much of an impact to the viewing audience to find it funny? If not, Amercian Dad is as good as cancelled.