This would have been a HIGHLY intriguing matchup 5 years ago. Now, both guys are washed up and it's kind of a "mehh" idea.
Froch exposed him as being extremely overrated, yet at the same time, he's clearly not as sharp as he was 4-5 years ago. Having said that, Kessler has always been the better fighter of the two.
Bute is not washed up physically. He's just a very weak fighter mentally. I don't think this fight happens, at least so early. Bute clearly needs a few tune up to get his confidence back. If he does so, I think he could beat Kessler, since he's not a guy who will test him mentally, and put pressure on him.