Firstly, no magical bullshit whatsoever outside of Dust, Aura and Semblances, if you count those.
Second, no more Salem. The Grimm are just a force of nature, there's no explanation as to where they come from or why, they're just here.
Third, each of our main characters realize their romanticized vision of a huntress isn't what they thought it would be, and their eyes are opened on what the world is really like.
Ruby discovers that heroes have to sometimes make difficult choices and sacrifices, she sees that people in many parts of the world either don't care for huntsmen or flat out hate them through missions they get from school. In the end she just accepts this but continues to try to be her ideal hero because "muh simple soul" or whatever.
Weiss, I frankly don't have a clue. I guess maybe she learns that running a business and fixing your families reputation takes a lot more than just fighting Grimm, and by series end she would probably quit being a huntress altogether.
Blake learns that she can't blame herself for shit thats not her fault, learns she can't fix the White Fang on her own and learns that being a shit and running away or not trusting your friends/family is a stupid thing to do.
Yang was already covered in the show pretty much. Wants to find out more about her mom, finds her mom, moms a bitch, she moves past that.
It's certainly not perfect, but I think it'd be better than all the shit we've got now.