We agree with Johnson's potential for a major letdown this week. From everything we have heard, Thomas is all but a lock to be out this week, and your analysis of Bell's upside (for this week only, probably) is spot on.
Johnson did have 69 yards on 16 carries (and a TD) against the Steelers last year, but that was a 16 game that was meaningless if memory serves. Bell should be able to at least match this type of production that is likely Johnson's ceiling for tonight's game.
Hope this helps - and we hope you'll listen to the podcast this week and in the future