> Your last paragraph is a new topic. It's true that Si can be as efficient as SiC and GaN, despite what the marketing usually says. But there are other benefits to new materials. They already support higher voltages with planar technology, and 3D will increase that further. Gate driving will get easier and more rugged.

There are 1000V+ silicon switches today which are not as fast, but have for, for example, very good RDSon. 1000V I think is an upper limit one would go for passenger car EV motors.