The Financial Times (via Kotaku) quotes a Japanese Analyst that this weeks change in management in the Sony Playstation division could mean no more Playstation hardware coming.

"The appointment of Hirai could be the start of a shift from hardware to software," said Yuta Sakurai, an analyst at Nomura. "I cannot now imagine a PlayStation 4."

I am all for focusing on the current Playstation 3, it will be years before we are looking at a potential next generation Playstation. That hardware is not everything is clear. Just look at the Wii. For Sony it is sure advisable to focus not just on prute performance of a console, but also on innovative game play and a strong network software infrastructure.
There will be a PS4, it might even have no disc drive. More Sony PS3 News.