From Jason La Canfora of NFL.com:

The Jaguars don’t expect any of their three “doubtful” players to go Sunday against the Dolphins, according to a team source.

WR Mike Sims-Walker (calf), DT John Henderson (shoulder) and CB Rashean Mathis (groin) are all being considered inactive by the Jaguars, with no expectation of a late turnaround.

That would leave the Jaguars without their top pass catcher, run stuffer and cover man for a game that ultimately could decide an AFC wild-card berth. The Jaguars (7-5) currently hold the spot, but the Dolphins (6-6) are only one game back.