My step-daughters were 5 and 6 years old in 1998 when Harry Potter first came out, the year I got married. They are now 18 and 19. In other words, the Harry Potter phenomenon coincided exactly with their childhood, from the point when they started reading to the point when they started college.
They truly grew-up with Harry Potter--I mean, the character. Their progress through school paralleled Harry's progress through Hogwarts. They read all the books--multiple times. We can quote all the movies. Everyone but me has a wand ;-)
Needless to say, we were at the midnight showing of the final installment of the series. And when it was over, there was this strange sense they had, that childhood was now over. They were now adults.
What is there, now, to look forward to? Life as we knew it is now over... ;-)