According to the information available from Microsoft Exchange Team, the on-premises release is planned to ship in the second half of this year (2015). As always, they convey the message that there are new features, enhancements, and refinements that add up to goodness on the way for end users, IT, and your organization as a whole. From the blog, some of the highlights of the new versions are,

• - A new approach to document collaboration that makes it easy to send links and collaborate without versioning issues of attachments
• - Faster and more intelligent search, to help users quickly find what they need in their mailboxes and calendars
• - Significant improvements to eDiscovery search performance and reliability
• - Better extensibility, including new REST-based APIs for Mail, Calendar, and Contacts that simplify web and mobile development

It is also unveiled that, some of these features are already birthed in the cloud, office 365 platform. Lets wait to see the enhancement that MS always committed to deliver.

Ref - Coming soon: A first look at Exchange Server 2016

I will try to grab information and share it with you all as and when it becomes available.

-Praveen