Hi there!
I am waiting for that feeling to hit me. Just been busy with the daily board stuff. I know that it will come though. :-(
Like Joanne said, there are re-reads, fan fiction/fanart, more movies to come, etc. Plus, according to JKR, she will be working on an encyclopedia. Fandom for HP is not done yet. Plus, we all still have our own imaginations and ideas of where the story would have gone, will go, and what happened before Harry and Company received their letters by owl that they would be attending Hogwarts (those many years ago).