Of course it's real! How can it not be when so many of us believe? It's real because we made it real. We read the books, watche the movies, ate the food, and cast the spells. How can it not be after all that? Remember this quote:
Harry: Tell me one last thing. Is this real? Or has this been happening inside my head?
Dumbledore: Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?
Why should it not be real when so many of us believe? When you believe in something enough, it becomes real. I learned that at an early age from the Velveteen Rabbit. Reality is just our perception of the world around us. I say that Harry Potter was mae real by us all believing in him. He's here, in our hearts. And he's not leaving. He'll always be there, just when you need him most. He's a friend, a brother, a protector, a hero. And he passed all of that on to us.