Lego's philosophy of these things is basically "If the company you're licensed with is done with what you've been marketing for, then stop marketing for it." However, I as an individual don't see it like that. Even though Harry potter is over, it's still a popular franchise. The novels are still selling strong, as well as the films, (which all have a fresh score on rotten tomatoes) and, who could forget Harry Potter? Really--just because the final movie came out doesn't automatically mean that it will be forgotten throughout time! Even non-harry potter fans remember our favorite wizard as that guy with weird glasses and a scar. The franchise is unforgettable. I still however, don't think lego will realize this and take it into consideration quite so easily. But, if you want to be optimistic, you could say that Indiana Jones' license lasted one more year after the movie came out (with sets like temple of doom, venice canal chase, shanghai chase, and Chauchilla cemetery battle.) and with lego superheroes, they're making sets for characters like the green lantern, (who's film came out months ago) Iron Man (Maybe a year) and Hulk. (a long time ago.) Why are they bringing them back? Because they're classics! Or maybe, (I dunno because I'm not hip like that) they all are getting a movie soon. Well anyways, putting that aside, if it is continued, here are my ideas:
The Department of mysteries
Minifigs: Harry, Lupin, Tonks, Kingsley S., Dumbledore, Voldemort, Bellatrix, and Lucius. (I would add more, but this is just me being realistic.
Cost: 89.95$ USD
Components: Shelves with prophecies, a red elevator, and an archway.
Detention in the forest (Also an add on to 4865)
Minifigs: Harry, Malfoy, Quirrel, (with cloak and hood) Firenze, and fang.
Cost: 29.99$ USD
Components: 2-3 trees and a Unicorn.
The Chamber of secrets
Minifigs: Harry, Tom riddle, Ginny, Ron, and Gilderoy Lockheart
Cost: 69.99$ USD
Compnents: Salazar Slytherin's face sculpture, Snake statues, and the basilisk.
The first task (Board game)
Microfigs: Harry, Fleur, Cedric, and Viktor.
Cost: 29.99$ USD
Components: Microbuilt dragon, rocks everywhere.
RavenClaw/HufflePuff tower (add on to hogwarts)
Minifigs: Luna, Cho Chang, Hufflepuff student,
Cost: 19.99$ USD
Components: Base of tower: Hufflepuff common room. Second level: Bathroom. (possibly Moaning Mertyl's.) Third level: Ravenclaw common room.