Inspired by IMAO ("Voldemort is the name of Harry's sled.") I thought I'd share a few Book 7 spoilers of my own...
5. To appease her critics, Rowling converts Hogwarts into a Southern Baptist Seminary.
4. All obscure symbolism is explained: e.g., Severus Snape ("sever his nape") is really Nearly Headless Nick.
3. The story is really about a murder mystery at All Hallows High School in the Bronx.
2. Harry is not a wizard after all. He was only joking.
#1 Spoiler - J.K. Rowling really has no idea where this story is going so has to sign another 7-book deal to try to figure it out herself.
Also, Time Magazine offers some future titles to keep the franchise going with the help of some subtle product placement like: HARRY POTTER AND THE PIMPING OF HIS RIDE - With his new bagless Dyson DC07, Harry has never flown faster, and Gryffindor has never been cleaner!
Update 7.19 - Another spoof by Lady Rose.