Everybody underestimates just how fast the capitalist system can switch if it's cheaper and/or more convenient. Even infrastructure, look at landlines. We're fast approaching that point with solar.
Now, for a south-of-the-Mason-Dixon suburban lot with good exposure, I believe I could build an off-grid home for only $10k more than when hooked to utilities. People forget that utility connection fees and installation costs are several thousand dollars.