Replacing a data source in Tableau retains calculated fields and all that goodness, but loses some elements of the original, in particular aliased dimensions and assigned colors. I'd like Tableau to appropriately transfer the aliases and color settings in the new data source, because the current functionality limits the use of "Replace Data Source."
An example is in the attached, if you replace the Sample - Superstore Sales extract with the Orders (Sample - Superstore Sales) Excel file, you can see the colors and aliases for the Product Category are both lost.
In the interim, here's a workaround (this says extracts, but can work with other sources): Let's say you're starting with file A.twb, extract A.tde, and extract B.tde.
1. Do a Save As... on A.twb to create a new file B.twb.
2. Close the B.twb.
3. Rename the original A.tde file to something like 1A.tde.
4. Open the B.twb. The "Extract Not Found" dialog will appear.
5. Click "OK" to locate the new extract. The "Locate Extract" dialog will appear.
6. Navigate your way to the new B.tde file, then click Open. Tableau will open up B.twb with the new B.tde and aliases and colors will be retained.
7. Save the B.twb file.
8. Rename the original A.tde file back to it's original name. This way the original A.twb will still be able to point to the A.tde file.