For performance considerations or isolated effect, softbody physics could applied to a specific Skin Gen mask since it has various material control settings. Instead of enabling it for the whole body, maybe your character is an android. In film or games, the fleshy areas will move but if the body contains painted on mechanical parts with subdivision etc, you may not want it to move and have it separate from skin areas.
A pair of Lungs could include various animations for types of breathing: Rapid, calm, inhale/exhale, Fear=anim mix to look random and dying -slows down to nothing, Resurrection -from nothing to a normal pulse . A heart -could also include most anim types as above. Veins - Could include similar as above. It would be cool to have scripts to attach to objects to trigger an animation type as well. For example Character 1 moves hand and directs a gun at character 2 and triggers rapid breathing.. as soon as the gun is lowered the breathing becomes normal. -things to speed up and automate the process.
Another update to what you be possible: If there is a threshold where the skin breaks from either inside or outside things like gunshot damage or a medical operation with a cavity added with organs etc would be pretty decent. We know the skin can already break, usually this is by adding the wrong weight map to the object/character.. maybe all what is needed is a copy of the weightmap that the soft body skin would use and make it real time weight map solver that can add other height maps as a mask (think shock wave gun hitting a body part in a water ripple effect) or bake procedural height maps to be added as height map animations. I've also made this request to a a developer on Unity (Obi develops assets that use Particle Based Physics (Cloth, Rope, Fluid, Soft Body) and is from my understanding the only one that has made a real time softbody physics asset on the Unity asset store. I'm hoping there could be an ideal pipeline between them both and with it an explosion of possibilities.