I don't see what is new or special here. Many A/C motors run without permanent magnets installed. Most induction motors don't have them. They are used to increase the efficiency of the motor. Early on in the design of induction motors, they were build as "wound rotor motors". These had a stator just like a modern induction motor but instead of a laminated steel and copper bar rotor, they used a rotating coil that was energized through slip rings to provide the rotating part that the stator would "induce" field into which made the motor turn. This allowed more control of the output speed of early motors before electronic controls were invented. A modern synchronous generator uses a small exciter generator that is mounted on the generator frame with a stationary field coil that sends A/C current into a wound rotor which rotates on the generator shaft. It's output is converted to DC by diodes also mounted on the shaft which then powers a rotating field inside the core of the generator that then produces A/C output power. In essence, this amazing new motor is almost identical to a standard synchronous A/C generator.
Before I would get too excited about this new motor, I would like to see what it brings to the table other than getting rid of the permanent magnets. The first Tesla's used induction motors but with the model 3 changed to a switched reluctance motor (which requires rare earth magnets) to get the range they wanted with the car. Even the new large Tesla's (S and X) use one induction motor in the rear for power and a switched reluctance motor for efficiency. When cruising at normal speeds, the front motor does most of the work.
