I've had the same thought about rotary motors, they're interesting beasts and I wonder what we'd see if they had the same R&D investment like we saw in piston engines.
Alas I think that ship has sailed, aside from energy density the modern electric VFD wins along a whole range of design constraints(torque, size, latency/traction response, efficiency, etc).
We have seen a significant long-term R&D investment but all the nice rotary engines are in prop planes.
Edit: since you mention a ship, some use large opposed-pistol Diesel engines (two oppositely meeting pistons around the combustion chamber per cylinder which also allows the cylinder to be much wider)... don’t see these in either planes or cars... Hydrogen power?—- Hydrogen is difficult to keep contained because it escapes through anything over time unless we put heavy ceramic tanks in our cars.
Unless you're talking about turboprops (jet engines with a gearbox) there really aren't any wankel engines in aircraft. Just a few experimental/EAB conversions out there.
Alas I think that ship has sailed, aside from energy density the modern electric VFD wins along a whole range of design constraints(torque, size, latency/traction response, efficiency, etc).