1) It would likely never be able to provide the type of sealing quality as in piston engines. Besides more sealing will be required than the piston. Piston requires sealing only on circumference. This one requires in on all sides of the vane.
2) I previously studied this rotary vane engine concept. In one of the patents, a problem mentioned was that when the vane uncovers the hole and the gases flow through, the hot gases will corrode the seal(if present) and the vane.
Over time this could be a major problem in this one especially since the corrosion will be taking place throughout the cycle of the engine.
3) Ceramics would be costlier than steel and aluminum. And they would require grinding and hot pressing to shape which is expensive though that might be partially offset by the lower number of parts.
4) Market scope:- I would say virtually zero because
a. no added advantage over the piston except power.
b. possibly expense
c. lack of research while the piston has been researched for over 120 years
d. MAJOR interest in fuel cells
e. restructuring of manufacturing equipment and tech know-how.