According to Bloomberg:
No new listings for the products will be allowed and posting of existing inventory will be removed Oct. 29, Amazon said. Amazon's streaming video service, called Prime Video, doesn't run easily on rival's devices. "Over the last three years, Prime Video has become an important part of Prime," Amazon said in the e-mail. "It's important that the streaming media players we sell interact well with Prime Video in order to avoid customer confusion."
Amazon recently launched new versions of its rival Fire TV and Fire TV Stick streaming video products