It's not just political reversal risk; there's the risk of technological obsolescence. It's very much a stretch to assume a nuclear plant will remain operationally viable (in the sense of being competitive) for 40 years, never mind the 60 or 80 years sometimes mentioned, because the competition isn't standing still.
The only credible competition against a state funded nuclear plant is hypothetical next gen geothermal power though.
Nuclear won't save the planet, as few countries can develop a nuclear industry. But for countries that have one, it should be a no brainer if not for irrational nuclear bomb fears.