Maybe he could decide, after we beat morganthe, that we are growing too powerful and must be eliminated. Then he will battle us, and if we win, we become headmaster and a new storyline unravels because penny dreadful was secretly helping morganthe, and when she was defeated, penny became the umbra queen.
Anthony Ashcatcher lv76 "Don't fight fire with fire, unless you have a convert"
I think that instead of fighting just Merle Ambrose, maybe all of the professors decide you are too powerful. There could be two seperate story lines. One if you are deemed to powerful and lose and a different one if you become the Headmaster/Headmistress. that would be really cool