That’s if you get one at all and when you do after waiting nearly two years it will have the old software ,interior and tech and it’s shell sat in a yard for months waiting for the parts. VW should be ashamed of themselves the way this Car has been marketed and sold.
Your assumption is wrong, VW aswell as other manufacturers work on a just in time basis (JIT) and do not close a line down but continue to make shells and store them outside. At the very most there maybe be a few bonnets and door skins that have been pressed and left on racks inside the factory.
If they were waiting for ECU or modules that didn’t arrive due to the chip shortage the line would finish with the cars fully painted and built and left on the production line, waiting for the electronic parts to come in and an engineer would go round and fit them installing any software at the same time. As @DumfriesDic said software is updated via a computer plugged into the OBD2 connector on the vehicle.
From what I understand VW carried on producing all but one varient of the ID3 to shorten lead times. If the line had been reporpesed for another model VW would have built the remaining ID3’s they had parts for and delivered them to customers. Based on the JIT system manufacturers are fully aware of their stock levels of various components.
Who told you this info your dealer?