Controversial here, but I think Dirrell would be too fast for Dawson who at 168 has slightly slower reflexes from making weight, could see a UD there.
Froch I could see applying the pressure and possibly forcing a close controversial UD. Dawson would land good straight lefts but Froch would just keep coming and maybe grind the victory. Depends on Dawsons pop at 168 as Froch is easier to hit than Ward.
Dawson would beat Abraham by decision provided he boxed him, but with Dawson's legs and chin a little shaky at 168 if AA catches him there could be a stoppage.
Dawson and Kessler would be a close one, still think Dawson has the speed and slickness over Kessler at 168 but again its how his legs would hold up to Kesslers bombs, otherwise could see a decision over this version of Kessler. Both styles would be difficult to one another.
Dawson beats everybody else by decision. Johnson, Green and Bute in my opinion are all tight at 168 like Dawson. Current Bute/Dawson would be a southpaw chess match, both weary of their stamina/chins, but I see Dawson's speed edging a close decision, although Bute's body punching could wear down Dawson late in the fight. Bute would have an edge in power but it'd be interesting to see whether their stances created the angles to capitalise on any chances one another gave.