I believe that Mike Bohn values integrity very highly. I remember when Gary Barnett was fired, he went out of his way to say, multiple times, that the University of Colorado honors it's commitments - and therefore CU was going to pay Barnett exactly what was remaining on his contract.
If it is true that Mike Bohn told Embree that he would have at least three years, then I would expect Bohn to honor that commitment, unless as Henderson wrote, attendance completely tanks, there is extreme division in the locker room, etc.
I do think that Bohn is very conscientious of the perception of the CU athletic department, and if he is concerned that other people (other coaches) will believe that CU didn't give Embree a fair chance to turn the program around, then he won't make a move unless he absolutely has to do so.