Mixed Content – With Mixed Content, we’ve made it easier for you to find the workbooks and data sources you need. The new experience gives you the option to see projects, workbooks, and data sources in a single list.

Check out the Mixed Content Help  documentation.

JDBC Driver-Based Connections – You’ve asked and it’s almost here! Due to customer demand, we have started working on adding support for using JDBC driver-based connections similar to the Other ODBC functionality in Tableau today.

Normalized Extracts – Normalized Extracts is a new performance feature for extracts with one or more join statements. Now, extracts can be created with a “Multiple Table” schema so that individual tables can be stored in the extract file before they are joined together.

Worksheet Transparency – Now you can enable set the background of a worksheet to transparent.

Set Actions – With Set Actions, we are allowing every Tableau customer to select what values are in a set by directly interacting with marks on a viz.

Sort Dialog Update – In Tableau 2018.3 we have updated the user experience of the sort dialog to improve usability.

Web Device Preview – With the new Preview Device Layouts page, the user can quickly see a preview of the visual device layout on the Web, using a desktop or tablet.

 
Rearrange Layout Button – The Rearrange Layout Button will run our new Auto-Generated Layout algorithm and quickly optimize your custom phone layouts.
Use the Test Scenarios and submit the Rearrange Layout Button Survey

Tableau Server on Linux Forward Proxy – Configure a forward proxy for Tableau Server on Linux automatically during installation.
Check out the Configuring Proxies Help  documentation.

Tableau Help Updates – We’ve made some updates to the look and feel of Tableau Help, to make it easier to find what you need.

Dashboard Navigation Buttons – Add easy navigation from your dashboard to another dashboard, sheet, or story.

SCIM for OneLogin – Provision new users to Tableau Online via SCIM for OneLogin

TopoJSON Support – Use TopoJSON spatial data files are now supported

• Density Mark Type (Heatmap)
• Tableau Bridge Admin Viz Improvements
• Connect to Google Big Query data
• Annotation Updates
• Filter Query Cancellation on the Web
• Duplicate as crosstab on the Web
• Dashboard image object on the Web
• Read multiple tables from spatial sources: ESRI Geodatabase and KML
• Set Action
• Automatic site invitation notifications for Tableau Server and Tableau Online
• Dedicated backgrounder per job types
• Go To Sheet Navigation Action

Note: Per Tableau, these features are subject to change.