I do wish my new car (Volvo EV) had a physical key for practical reasons (having a place to put it and thus remember to bring it with me is an underrated feature of car ignitions) but I don't think there is anything that fundamentally makes it impossible for CANBus attacks to work against cars with proper keys.

I highly doubt that modern car ignition locks are not also just sending a start signal via the CANBus. If they had a physical wire to trigger engine start it seems like that would make hotwiring the car easier, since I believe that is how older cars worked?