I really hope that I won't surprise anybody saying that SQL Server 2016 is just around the corner. It is now in technical preview if you have a spare machine (or a VM) to test it. The publicly available CTP is available from http://www.microsoft.com/en-ca/server-cloud/products/sql-server-2016/.

A free e-book is also available from http://blogs.msdn.com/b/microsoft_press/archive/2015/12/22/free-ebook-introducing-microsoft-sql-server-2016-mission-critical-applications-deeper-insights-hyperscale-cloud-preview-edition.aspx. They even have a smaller PDF version optimized for mobile reading.