SharePoint Server 2019 was announced by Jeff Teper at the recent Ignite 2017 conference. Microsoft has released little details to date though some of the “big bets” it listed in this blog post are:
- Next-Gen Sync Client support
- Modern UX throughout the product
- Flow / Power Apps integration
- Other SharePoint Online innovations
SharePoint Server 2019 is currently scheduled for release in the second half of 2018 according to Jared Spataro in this Office blog post.