Absolutely - the question is if it makes sense as a business move for Tesla, it would basically destroy the Powerwall as a product (though I am skeptical they sell a lot of them, compartively). And if they could also overcome the regulatory hurdles, electrical code is fairly strict (for good reason!) I have a roof full of PV I'd love to use during power outages, and a PHEV in the driveway I'd happily swap for a Tesla if they could connect the dots.