Titan already does do something for mountain buster. It is right left swipe animation on tank, then mountain buster. As healer the moment I see that swipe I know to spam heals in phase 5.
Titan also randomly turns away from the tank right before a landslide.
So yes there are already cues. I don't have phase 5 memorized. I react to what I see coming next based on Titan's animations.