Students mostly graduate in 3 years, why not also add masters and PhD, with extra requirements for teacher level and available rooms.

Most probably you already have this in your development timeline.

I can see this as a DLC/expansion idea. Great thinking

Oh wow. This is an excellent idea, actually. I'd never even thought of that, that's actually a pretty awesome idea.

I would like it 

Would be nice to basically let you get "free" upgraded staff as well, since doctoral students usually do student teaching and some could also become professors down the road, once they graduate.