On this topic, it is known whether the new Model S/X motor is interchangeable with one in the Model 3 - or is it a new variant of the Model 3 design?
Would have to be new variant of the drive unit. Even if the 3 rear and S/X front motors used the same gear ratio and mount points, Tesla biases the motor to the center of the vehicle.
The motor core (rotor and stator) is most likely identical. FWIW, the stator press fits in the drive unit housing.