If the movie is overtuned (sucked) then Blizzard will release a patch for it (Director's Cut Version).

From Wiki:

"In August 2007, at BlizzCon, it was unveiled that the film will aim for a projected 2009 release. It was also revealed that the movie will take place from an Alliance perspective and will be geared towards a PG-13 audience, with a storyline set one year before the beginning of the World of Warcraft storyline.

...As of September, 2008, Chris Metzen has been slated to write the film. At Blizzcon that year Metzen and Producers from Legendary Pictures stated the story would revolve around a "Kick Ass Human Character", which would not be Varian Wrynn, the then-unannounced hero of the comic."

Rise of the Lich King is just a hook title I feel, like Rise of Cobra in the G.I.Joe. What rise of Cobra, the dude wore a new mask in the final few moments and promptly gets arrested right after that.

I can already imagine the end of the WoW film: after a mistaken conflict between Alliance and Horde, the film cuts to show (maybe even as an post-credits scene) Arthas' eyes snap open and snickering as he awoke from his slumber on the Frozen Throne.