Looking at the history of the last Microsoft releases, it looks like the release of SQL 2016 will be either March or April.. Hope my prediction is right:)
SQL Server | Release_Date |
SQL Server 2016 | 2016-04/03-?? |
SQL Server 2014 | 01/04/2014 |
SQL Server 2012 | 06/03/2012 |
SQL Server 2008 R2 | 21/04/2010 |
SQL Server 2008 | 2008-08-07 |
SQL Server 2005 | 07/11/2005 |