Before we get started here, let's make clear that the Felix Sturm vs Daniel Geale fight isn't off, and that it doesn't appear that's even a consideration. Sturm, who is promoting the fight in Germany, says he's waiting to see what Vitali Klitschko does for his next bout before he settles on a date for the middleweight trinket unification fight with the Aussie.
Now, it appears there's an issue with September 8, and that K2 has the TUI Arena in Hanover, Germany, reserved, which is where Sturm wanted his fight. All reports I've seen are that Vitali is going to be fighting in Kiev, not in Germany. Even still, they wouldn't want to clash their TV dates.
Honestly, I'm having a tough time keeping heads or tails of this. As best I could tell a couple days ago, Sturm-Geale would be September 1, and Klitschko-Charr September 8. So maybe there's really no worry at all, and this is just a case of Sturm being safe rather than sorry. He understandably has no desire to go head-to-head with a Vitali fight, especially one rumored to be Vitali's farewell outing in the ring.
Hopefully if anything gets canceled, it's Manuel Charr and not the good middleweight.