We know Office 2019 is due out in the second half of 2018. The recently updated release details confirm the products that will be available (usual apps as well as Exchange, SharePoint and Skype for Business servers) and that there will be 5 years of mainstream support and 2 years of extended support. Technically speaking, Office 2019 will only run on Windows 10 and will only be available with Click-to-Run installation technology.

Find the release details here: http://bit.ly/2nw9gOx, an FAQ about Click-to-Run here: http://bit.ly/2KIIT16 and general Office 2019 FAQ here: http://bit.ly/2w3TCxA.