Office 2016 does not introduce any new features for add-ins:
Macros and Add-ins—We’re not making any changes to Macros or Add-ins in this release. It’s rare that “no changes” is a something we’d want to highlight, but we think it’s worth celebrating the consistency in the programming model across releases. We understand how important this is and we’re committed to a high level of compatibility as we continue to innovate. (See dev.office.com for more on how we’re innovating in Office extensibility.)
http://blogs.office.com/2015/03/16/announcing-the-office-2016-it-pro-and-developer-preview/
