The latest work on Wayland's Weston compositor is working in the direction of making it support run-time switchable renderers, such as between the OpenGL and Pixman renderers or theoretically different GL renderers.
Landing today in mainline Weston is a change by Intel's Ander Conselvan de Oliveira to allow Weston renderer back-ends to create and destroy surface state of their own. Right now there's the OpenGL, Noop, Pixman, and Raspberry Pi renderers that are impacted by this compositor change. The overall direction of this work is taking a step towards allowing Weston renderers to be switchable at run-time.
The commit moving Weston closer to supporting runtime switchable renderers is compositor: Let renderers create and destroy surface state on their own