I don't expect JB to be the type to linger around. I think you will see him disappear in the proverbial puff of smoke. When he is done, he will be done. He is smart enough to know that the last thing Hop will need, is to have him breathing down Hop's back. JB has ego, you have to in order to be at the pinnacle(or near pinnacle, depending upon how negative you want to be) of your profession. Also, JB has been adamant about not leaving too early, and having regrets.
Having said that, It is hard to believe that Hop would spend years teaching, and extolling the virtues of the 2-3, just to do a flip-flop as soon as the head gig is his. I don't he makes much change in the first couple years. He will then likely start to mold things more to his personal tastes. He is a high energy guy, so it is easy to imagine him putting more emphasis on a pressure type defense or wrinkle to the base 2-3.