The 70-339 exam will test you on the following topics:
- Design SharePoint infrastructure (15–20%)
 
- Plan authentication and security (15–20%)
 
- Plan workload optimization (15–20%)
 
- Plan productivity solutions (15–20%)
 
- Manage search capabilities (10–15%)
 
- Plan and configure cloud services (5–10%)
 
- Monitor and optimize a SharePoint environment (10–15%)
 
The path for the SharePoint 2016 MCSE is not yet released, but if it's like the 
MCSE: Messaging (Exchange 2016) exam path, the path for the SharePoint 2016 MCSE would be the following:
- 70-346 (Managing Office 365 Identities and Requirements)
 
- 70-347 (Enabling Office 365 Services)
 
After successfully completing steps 1 and 2, you’ll earn a Microsoft  Certified Solutions Associate (MCSA): Office 365 certification.
- 70-339 (Managing Microsoft SharePoint Server 2016 (in development))
 
To view more information about the exam from the Microsoft Learning site, check out the exam here: 
https://www.microsoft.com/en-us/learning/exam-70-339.aspx .
Source Info: 
https://absolute-sharepoint.com/2016/05/microsoft-releases-sharepoint-2016-mcse-information.html