It appears that Canon continues to research image stabilization in tilt-shift lenses. Are we possibly going to see more tilt-shift lenses in the future with IS? Or are we a ways away and likely won't see such a thing until the next updates in a decade or so.
From Canon News:
Japan Patent Application 2017-227697 deals with the wiring of the IS elements that tilt and move with the corresponding tilt of the lens. Specifically how to optimize that because to provide the flexible interconnects necessary for the IS unit would increase complexity.
We haven't anything about more tilt-shift lenses, I think it's safe to say that the latest 3 will be it for a while.