First, hopefully Ben Roethlisberger will be fully healthy soon.
I'm not sure if the Steelers losing Roethlisberger will work to the Lions advantage. The Steelers probably will depend more on their running game than they planned to with Roethlisberger . This could open up opportunities in their passing game against a Lions Defense that has given up a high number of long gains against the pass.
Also, any chance of the Steelers not being focused enough from a Steelers perspective is all but out the window. On the other hand, the Lions might lose the edge needed for this game. This is a very young Lions team that could learn the hard way not that the Steelers often find ways to overcome adversity.