Given Tesla’s currently tiny market share (less than one third of one percent), the only way this will happen is if major car producers take advantage of Tesla’s open patents to start producing electric cars themselves.
Musk has publicly stated that new technology often only can be made for the luxury market in its first instance, and only when it enters later generations of production can it be created at mass scale, becoming affordable to the general public, although this is a long term goal.
Incidentally, car companies have lobbied voraciously against Tesla in a number of states. It is illegal for Tesla cars to be featured at showrooms or sold in Michigan. Despite free market protections it seems that innovative technology can be subverted through corporate influence over politics.
On a brighter note, Musk mentioned that his son called Model S ‘the stupidest car ever’ because it didn’t have backseat lighting for him to read at night. Despite Musk’s advocacy of the car, he agreed with his son and directed his engineers to reinstall backseat lighting.