I don't consider the Lions two games up on the Vikings and Packers because if either team beats the Lions at Ford Field and otherwise matches the Lions the rest of the way (or in Green Bay's case, otherwise outperforms the Lions by one game, it goes to a tiebreak. I think the Lions are way ahead of Minnesota on conference record but I think too early to assume that's in the bag. So if the Lions and Vikings both go 4-2 or 5-1 and then Minnesota upsets Detroit in Detroit, then it goes to the tiebreak. I think the Lions will beat Minnesota handily in the final game of the season, so it would be a moot point, but I'd rather not have to go into Week 18 worried about it.
So I'm most worried about Minnesota. I think Green Bay and Philly are better teams than Minnesota. But Minnesota is the biggest risk of snatching the division title from the Lions and knocking them down to a #5 seed. I think the Lions go to the Super Bowl as long as they're at least the #2 seed. #1 seed, a bye, and 2 home games is ideal. But I think that they're good enough to go #2 seed, 2 home games, and road win over Philly even in bad-weather January. But #5 seed needing 3 road wins to win the NFC? That's a tall ask.