Not really. German car companies buy most of the parts from suppliers. Those suppliers often have decades of experience with electric motors and batteries, see Bosch. If a supplier only does ICE components, they are out and the car company will find a new supplier.
There's a technology race on, and Tesla are clearly pretty aggressive in pursuit of innovation. I don't think the possibility of them having a lead over German companies as regards batteries is far-fetched at all.
