The Human Centipede 3: Final Sequence was expected to begin shooting this May in the US. It was recently revealed that both Dieter Laser and Laurence R. Harvey were set to star in the film, but supposedly problems with Laser have forced a delay in filming.
Producer Ilona Six sent out a statement, saying that they were suing Dieter Laser and filming will be pushed back to later this year:
“Because of the success of THE HUMAN CENTIPEDE, it seems that Mr. Dieter Laser’s ego has grown to laughably big proportions. First signing the contract and rating the HUMAN CENTIPEDE 3 script as fantastic, and then demanding his own unacceptable script changes, and now refusing to play the part only seven weeks prior to shooting. Six Entertainment Company will start legal action against Dieter Laser. Tom Six says not to worry—principal photography will be postponed and will take place later this year.”
As others have suggested, this may be a publicity stunt. With the third film presumably following the footsteps of the second film and taking place in the "real world", this may be part of the story. On the other hand, if filming is actually delayed and there are casting changes, we'll be sure to post an update to this story.
**Updated: Under The Gun has a statement from Dieter Laser:
"It’s very simple: I loved the story when it was told, got the contract and the promise to have the script in 4 to 6 weeks. When it arrived – half a year later and only after the official announcement – I didn’t like the realization at all, couldn’t identify with the character the way it was written and developed immediately and enthusiastically in a day and night marathon a version full of concrete and practical suggestions which would enable me to play the lead full throttle – same procedure as with Dr. Heiter – but this time it also would have had some unavoidable effects to the dramatic structure. That was too much for Tom and since he couldn’t live with my suggestions and I as a method actor couldn’t identify with his version, I told him that I couldn’t see any other way than that he would have to “change horses”. That’s it."