No tilt/ no servo/ no Y6 Tricopter

I was told that the only way you could get yaw authority on a Tricopter was to build it with a servo tilting rear motor or a Y6 configuration. a friend sent me a link to this study showing that its maybe possible to design and fly a no tilt/ no servo tricopter. 1. is this actually possible? (in the document he only runs it on a simulation) 2. would arducopter ever support this configuration?
here is a link to the paper