I enjoyed the movie, it's definitely one of John Hughes' best.
That said, I don't think it needs a sequel.
Same with Fast Times at Ridgemont High. Decades from now, I'd be surprised to see Slow Times at Ridgemont Retirement and Assisted Living Center.
I'm sure the movie is still somewhat relatable today, but why not have a different movie of the same vein for the current generation? It doesn't have to be recycled, and they can touch on more contemporary topics, especially since school is much different today than it was for us in the 80's.