Even if KG returns, he apparently really doesn't want to play center. Moving up for Drummond, Leonard or Zeller--and hoping he turns into a future starter--would interest me.
Also, if he stays where he is in the draft and, say, Nicholson is the best player available, I think he takes him and doesn't worry about a guy who couldn't even get Doc to dress him for the games (figuratively, that is) last year.
Finally, as to the 3's, I think there may be some future starters in Harkless, Miller or Fournier available, and there's no reason for Danny to pass on them because he might have Jeff Green back next year.