Let's start with something simple and fun. Ignoring the many variables that go into a detailed analysis of an NFL team's season forecast(strength of schedule, personnel movement, age, leadership, injuries, etc.), what does history say about the Saints' chance to repeat?
If we look at history of the NFL since 1966, there have been 8 repeat winners of the Super Bowl, with the Steelers doing it twice(1974-1975 and 1978-1979). No team has pulled off a three-peat. On only 3 occasions has the defending Super Bowl champion played and lost in the Super Bowl the following year. So if they get there again, history says they will win it. 13 times the Super Bowl winner has not made the playoffs the next year. This has happened to the Steelers three times. The remainder of the time(19), the Super Bowl champ has been eliminated in the league playoffs.
So, based solely on historical trends, it is highly probable(70%) that the Saints will make the playoffs in 2010 and they have a 19% chance of repeating as Super Bowl champions. What do you think?