Edison’s vision for electricity was similar. In his conception every block would have it’s own private electric generator providing power for a dozen or so homes. Economies of scale dictate, nevertheless, that you save a lot of money by building one gigantic power plant rather than by building a thousand small ones.
That's true as long as the efficiency at the one gigantic power plant is higher than thousands of smaller generators.
But, transmission line losses reduce that efficiency. If you can achieve better efficiencies locally and can use the excess heat for something else (like hot water or heating), it starts to become viable.
There's also the maintenance issue: a mechanically driven generator is beyond the ability of many people to keep running properly, not to mention the noise. A silent, low-maintenance fuel-cell generator would be more practical.
In the end, it will depend on how much it cost to "feed" the generator, and whether the effective cost per kilowatt hour is less than getting your electricity from the grid. The difference (and your usage) will determine how long it takes to recoup the cost of the generator.