I agree that new nuclear power doesn't appear to be competitive with new renewables in the near term. It might be competitive again as renewable penetration gets high and storage costs rise. If there were just one tax incentive scheme, aimed at reducing CO2 emissions, we could be sure that tax incentives were optimizing for low emissions without distorting the market in favor of overly specific technology choices. But as I mentioned before, I'll take the overly specific and distortionary incentives if the alternative is "no incentives at all for reducing emissions."

It's probably needed in northern countries for COMPLETE decarbonization. And basically all large infrastructure has some level of subsidy, definitely including wind, solar, and hydro.