Why not imagine a future where fusion technology improves to the point that there's no point in using anything else? With fission, we're already there, and taking full advantage of fission now, with breeder reactors and spent fuel reprocessing made legal again, will give us the energy to pursue fusion worldwide with a budget similar to the U.S. defense budget. Sticking to solar and other "green" energy means mass-homicidal energy austerity!
The tech is there, only breeders are quite expensive, anti nuke lobby and politics screwed things up to such a degree that nuclear became overpriced and overengineered. Still we can fix things, SMRs such as NuScale (basically naval scale PWR tech) are a solution if the licensing hurdles are be resolved and so is geothermal where it's available.
