Roadmap after Exchange 2016 for on-premise

Perry Clarke, Corporate Vice President Microsoft Exchange, wrote:

• "The Exchange engineering team is hard at work developing the next version of Exchange.
• We expect the next on-premises version to be released according to our traditional release cadence (2-3 years after the previous version).
• Microsoft has no plans to stop delivering on-premises releases of Exchange.

....

While we are enthusiastic about the cloud, we also understand that our customers will transition to the cloud at their own pace. Many customers will remain on-premises or in hybrid deployments for the foreseeable future, and we want to keep delivering our newest and best features to them. Fortunately, our development process allows us to do that. We have a single code base that serves both cloud and on-premises customers, so we can deliver innovation to both groups."

See Exchange Server: The Road Ahead