Happens all the time in the automotive industry. The first "american" hatchback car I ever drove had a nice VW engine. Ironically it was something to do with low emissions.
But then most applications outside "quick 0-60 pure electric car" use brushless DC motors instead, where the controllers are simpler. Even the insane McLaren P1 hybrid, which eats Teslas for breakfast, uses a brushless DC motor. So I'm not sure there is as much of a market for Tesla's expertise as you'd think.
If it's all truly Panasonic's tech, I am surprised so many people put their money into Tesla.
http://pop.h-cdn.co/assets/15/07/980x490/landscape_142375080...
Tesla Home isn't doing too hot, as far as I can tell. Even SolarCity isn't recommending it to anybody... and SolarCity is Elon's baby as well!
Whether they will achieve that is a different (and still open) question.