I think it depends on where Sutter sees Dube in the lineup. If Dube plays in the top 6 then I think it is Lewis' place to lose. Lewis - Backlund - Coleman seemed pretty good at shutting teams down last year.
If Coleman plays on the 2nd line then I think Sutter tries Lucic. Lucic - Backlund - Dube as a 3rd line that's hard on the forecheck with a good cycle game.
Personally, I hope that one of Pelletier/Ruzicka/Phillis takes the spot and runs with it.
I don't think there is any chance of Lewis moving up from the 4th line - his role is clear and set
During the regular season last year that line played for 80 minutes together, with decent analytics and an xG% of 54.5%. Now I don't think it would be an ideal 3rd line, but I think it might be a line Sutter uses to start the season.