For weeks, billboards promoting the finale of Warner Bros.’ Harry Potter film series, which opens today, have sought to lure viewers with the prospect that one of the most lucrative properties in Hollywood history is about to conclude, declaring: “It All Ends.”

But for Warner Bros., the task is now the opposite: make sure the business of Harry Potter doesn’t end, even without another blockbuster film in the works. That will take some magic.

Over the past 10 years, Time Warner Inc.’s Warner has turned the popular books by J.K. Rowling into an enterprise that spans videogames, toys, a theme park and other businesses. It’s a machine that has spawned nearly $20 billion in retail sales for Warner and its partners and added $1 billion to the studio’s bottom line, making it one of the most valuable film franchises in modern Hollywood.

In interviews this week, Warner executives outlined plans for how they hope to maintain their Harry Potter business after the final film installment. The plans include a likely expansion of Harry Potter theme parks around the world and new investment into Harry Potter-related online businesses and videogames.

The bet is that instead of the franchise slowly fading away, as many do once big screens go dark, Warner can profit from the boy wizard far into the future. “We obviously think Potter is an evergreen property,” said Barry Meyer, Warner Bros.’ chairman and chief executive. “This is not something that ends with the film franchise.”

Follow this link to read more: