I'm more concerned about the Chiefs, Chargers and Ravens than the Steelers at this stage. I think the Steelers have a tougher schedule than the Bills anyway (vs Packers, at Chargers, vs Bills, Ravens x2, at Lions) so they'll drop a few games.
The Vikings seem ripe to beat up bad teams where their defense can keep them in a game, but the offense is nowhere near good enough - more specifically at QB - if they need to win a shootout.