I can see Burke leaving as a grad transfer no matter if Hoiberg wants him back or not. He was recruited by a different coach into a completely different system. He didn't really have a choice to leave after Miles was fired. If he left, he would have had to appeal to the NCAA for immediate eligibility or lose a season (play 3 in 5 years). And we all know how silly the NCAA can be about appeals.
Mack is going to be a tough call. Does his on court talent out weigh the off court BS? There is no doubting the on court talent and potential but he's not Michael Jordan so you can't have a different set of rules for him like the Bulls did and you also can't have your point guard getting suspended constantly. If the off court BS had been early in the year and he had shown signs of maturing through the year, I think it would be a no brainer that he stays, but it has been the opposite.