Sources have informed the Wall Street Journal that Sony aims to release the PlayStation 4 in 2013. They also mentioned to WSJ that the developers were throwing around the idea of making it download-only, but scrapped for the obvious reason of limited connectivity to the Internet around the world. Even I have trouble from time to time. GameSpot asked for comment from Sony on the matter, to which they replied with a sort of non-reply, "This is rumor and we do not comment on rumor."
That probably would have been the failure it was last year with the PSP Go where the PSP outsold it in Japan 1,000-1. Yes, 1,000 to 1. Oh and the report also says that the new Xbox will have an optical reader, possibly indicating a Blu-Ray Drive.