No official announcement has yet been made by Capcom, but keen-eyed user Tripp3K on the Koei Warriors forums noticed two days ago that Play-Asia was listing a new PS3 Sengoku Basara game release for late March 2013.
Some smaller independent shops had posted the game as an upcoming title as well, but everything seemed very vague. However, media giant Tsutaya has now posted the details and Play-Asia has followed suit with some additional information, so it looks as though this is confirmed. I anticipate a confirmation from Capcom very soon.
It was nothing terribly exciting in the end: Sengoku Basara Triple Pack is to be a PS3 bundle release of Sengoku Basara 3, Sengoku Basara 3 Utage and Sengoku Basara HD Collection. As the HD Collection contains Sengoku Basara, Sengoku Basara 2 and Sengoku Basara 2 Eiyuu Gaiden (Heroes), this 'triple pack' will actually include five complete games: that's every single title in the Sengoku Basara series other than the PS2 fighting game (Sengoku Basara X) and the two PSP spin-offs. It will be released on 28th March 2013 and its price will be ¥6,990. This will be a great way for newcomers to the series to grab all of the PS3-compatible games in one go at a very attractive price.
Of course, most of the people who actively follow Sengoku Basara news probably already have some (if not all) of the games in the Triple Pack. Since Capcom can't really squeeze any more money out of the existing fans with this kind of release, I'm hoping that there'll be some news for the rest of us as well in the near future!