I'm going to propose either members of the Tableau community or Tableau itself create a WMS server. It would need FTP (to allow duplex file transfer of files) and an administrator.
Backstory: In the last few months, I've noticed a demand (requests) on the forum for data such as:
etc, basically anything that the third-party doesn't support "out of the box" (or within the licence terms).
All of which have readily available raster and vector files. If you need to interrogate shapefiles, then Richard Leeke's tools can be used. However, if you want to layer GIS data to show HRO (GeoTiffs) or multiple vector layers (Shapefiles) then WMS is the way to go.
To decrease my dependency (I wanted an offline, layerable, GIS capability), I downloaded Geoserver and discovered that it was capable of drawing other projections other than WGS84 EPSG:4326 onto the Tableau canvas, with no visible distortion. Below, an example of USGS HRO running from a locally served instance of Geoserver as a Windows Service. Note the map options! The tile is being served with the correct datum (EPSG:26912). That alone prompted this idea.
Crowd Sourced GIS data
If the community deems this a good idea, it would be possible to create a hosted Geoserver and FTP the files required to serve. I think that with the demand to visualize layers of non US centric GIS data (both vector and raster), that the community could populate this with what they need/want (as long as the data is open source). Tableau is a global product. Data is ubiquitous.
I love Tableau. I love BI. I love GIS. Please, let's be the market leaders by combining both - it IS possible.
The map option layers reflect the admin GUI.