First off I know there are MANY permutations here. I don't want to toot my own horn, but I've been pretty good at this in the past. The best case scenario would be Ravens winning this week and losing next to the Rams. That gives the Steelers a straight shot if the expectedly lose to KC today.
For the purpose of discussion, I eliminate the Browns as without beating them at home next week everything is moot.
Which brings me to the most likely scenario:
The Steelers/Bengals trade losses to KC over the next two weeks and The Bengals beat the Ravens this Week and the Steelers beat the Browns next. The Steelers are the half game behind and it goes to week 18. The Steelers will need to beat the Ravens and need the Browns to beat the Bengals. The Browns will be game. It will be a similar situation to a couple years ago where the Browns damn near helped the Steelers against the Ravens.
My two cents.