If you judge by this article by Mattew David at InformIT, the answer may very well be yes. It seems that some of the machinery is in place.
As you can see from the browser attempt below, the Flash client can read in an XML file and an accompmanying CSS file for the styling. I'll explore this further later on, but it sure seems promising for the future of rich web clients
You can have look at the sample.html ( rather XML instance ) and sample.css here.
Note that these files are external to the Flash movie ( the SWF ) and loaded and parsed dynamically, using the XML and TextField.StyleSheet objects!