I actually think it would be interesting if there was a standard interface between the renderer and the browser ui. This would allow renderers to compete on th

I actually think it would be interesting if there was a standard interface between the renderer and the browser ui. This would allow renderers to compete on their own merits with their real customers (developers), instead of being shackled to the success or failure of their attached UI. OTOH, one potentially bad outcome would be that there would be increased stickiness of content. Once content is authored targeting one renderer, there is little reason for authors to update it since they can always target the old renderer.