CSS Backgrounds and borders defines a way to create a scale 9 image: http://www.w3.org/TR/css3-background/#border-images I propose to extend this feature to SVG, but instead of slicing an image, we would define a new tag <brush>.
This brush can be set as the color of the stroke. The stroke width would affect the scaling of the brush element.
Examples of border brushes in Illustrator
A simple google search for border image
Example how the sides start to tile when resizing the path]
Example how the stroke width affects the borde
Example how dashing affects the tiling
Example how tiling is used on different shapes
<brush id="mybrush"> <corner bbox="..."> ... </corner> <side bbox="..."> ... </side>
corner and side can contain any path data but can only solid colors. This is because if will be too hard to deform images and gradients along a path,