I don't know how correct my view is, it could be totally dreaming, but here's what I have in mind:
Apparently, thinner diaphragm in a driver is usually a good thing, thinking of electrostatic headphones' super thin diaphragms.
Now, graphene has been found and studied for some years, and it is known to have very high electrical conductance, and also very strong physical strength. People in material science has been able to produce graphene to the size of a normal driver membrane (say ~50mm diameter) to probably ~100 nanometer thickness. My knowledge of graphene is very out of date so it could be even better.
Although I know that diaphragms are used differently in dynamic, planar-magnetic and electrostatic methods, so I'm not sure if the high electrical conductance is a good thing, but at least it seems to be worthwhile considering...?