I agree.
Don't forget we will need a new transfiguration teacher in the next book too. McGonagall will be the new headmistress. Harry will have to be back in the school at some point, maybe that will come to something. I still think there may be a Horcrux hidden in the Room of Requirement with the potions book. Maybe at some point Harry will at least go back to retrieve the book (to get to Snape, or find out more about him and something in the room will catch his eye...)
She's a tad young for it, but it would be a perfect job for one Ms. Hermione Granger.