TDK isn't the only one developing multi-layer Blu-ray discs. According to an article at NikkeiBP, Matsushita (Panasonic) has developed a 4-layer 100GB disc. Aimed at long-term storage, the media is expected to be playable after 100 years.
Matsushita Electric Industrial Co., Ltd. has developed a 4-layer Blu-ray Disc (BD) medium using Te-O-Pd film for inorganic recording layers. Total capacity reaches 100 GB with each layer having 25 GB storage capacity. This is the company's first report of four-layer BD discs. By revising a Te-O-Pd composite proportion, the company reportedly achieved durability that allows data playback after 100 years.
I wouldn't get too excited yet. TDK developed their 100GB disc back in 2005 and the technology still has not made it past the prototype stage. If you'd like to read more, the entire article can be found here.
