I wouldn't worry about that, there are many renewable sources of energy that can satisfy our energy demands for eternity. I'd like to see Moon as a base for our interstellar travel, given the low gravity, we can launch spaceship deep inside the solar system, and probably reach Mars in few weeks, hence another option for future colonization.
Another prospect for moon will be asteroid mining, we can place an asteroid in moon's orbit, and mine the asteroid for valuable metals, water and other hydrocarbons and use it to build space structures on moon, and to launch them into space.
By launching from moon, we can build even bigger structures in space, and If we can get water on space by mining asteroids, then farming won't be a concern using advanced aeroponics. We can sustain living in space with artificial gravity. We born on earth, but we never meant to die here. If global power comes together, forgetting wars and animosity, Mars can be terraformed within the next few hundred years.