According to the latest report from Mary Jo Foley, Microsoft is planning to release Office 16 release only in second of 2015. Microsoft released Office 2013 back in October 2012. Releasing a major update in second of 2015 is highly possible given their track record of releasing major updates every 2-3 years. General Manager of Office and Office 365 Marketing Julia White revealed this tentative schedule during TechEd earlier today.
Microsoft has also confirmed that the next versions of Exchange Server and SharePoint Server will be released in the second half of 2015. Microsoft has already started testing of Office 16 with limited people in the public community. We recently revealed all the new features coming in Office 16. Earlier this week, screenshots of upcoming Outlook for Mac 16 also got leaked.