I'll put it this way. This Saints team can play with anyone in the league. I think it's very hard to ever have a clear cut "best" team in the NFL... and I think there's a lot of teams that would split games 50/50 no matter how many times they played.
There is always a chance... but I wouldn't count on it. Let downs are almost inevitable. A bad week of practice, off-field distractions (ever been distracted at work? These guys are human, too), etc. Then you have injuries, which we're already seeing and will continue to see as the season progresses. The "big one" could be right around the corner for all we know.
If the Saints were able to consistently peak out and play complete games from now until week 17... and suffer no significant injury setbacks... they could beat every team. They are that good, IMO.