Solar generation can be had, for reasonably sunny sites, for abut $/kW, which puts it ahead of grid. Wind, since the advent of neodymium permanent-magnet alternators in kWish sizes, is also becoming competitive (and a solar/wind combo tends to balance nicely against available load. Alternators are electronics and the Moore's Law improvements are also bringing them down (though the economy of scale isn't there, yet.)
The big missing piece has been a high-capacity, long-lived, low-toxicity energy storage system, to cover calm nights and other weather variations. (Thee days of storage, in halfway-decent renewable energy sites, means you only have to run the backup generator a couple times a year - which you have to do, anyhow, to keep it from rotting internally.)
So these battery improvements should be enabling for off-grid housing, as well.
Won't kill the grid, though. Because all these electric cars will need charging - at several times the consumption of a house. Even in the good sites, adding an electric car to the load bumps the generation's capital cost up again, big time. Win some, lose some.