The Messmer Plan actually built cheap reactors, so you undermine your own argument there. The point I made was that costs started increasing as they managed to meet their electricity demand. You cannot keep up high volume production once most of your power needs are met. You can only build as electricity demand increases or old reactors need replacement.
Contrary to your argument the long lifetime of a reactor is in this case a negative, not a positive. It means you need to build new reactors so seldom that you end up with very low volume production. Low volume means high cost.
Because wind and solar needs far more frequent replacement you end up with much higher volume production, which means lower cost. What do you think the price of smart phones would have been if millions of people did not replace them every year? What if people bought a new smartphone only every 50 years akin to a nuclear power plant? Prices would have been astronomical.
The fact that France used a government project to build nuclear is a large reason why they manage to keep it cheap. Free market nuclear power works quite badly. The investment is too high and risky. The return on that investment comes too late. There is a much stronger incentive for markets to invest in wind and solar as risks are lower and returns quicker.
As for your 1 kWh comparison. Levelized costs calculations exist. These take into account depriciation, subsidies etc. And wind and solar clearly beats nuclear power in these comparisons.
As long as your grid already has lots of fossil fuel plants which can be fired up, there is no need to count cost of storage when comparing. If you got two fossil fuel plants, and your nuclear plant replaces one of those for 10 billion, then emission cuts will be no different than if my wind and solar parks built for 10 billion doesn't shut down one plant but make both plants only run half the time. The net effect in terms of CO2 emissions is basically the same.
For fossil fuel plants a major part of the cost if fuel. Thus when wind and solar lets e.g. a gas power plant power down, they save a lot of money.
Of course powering up and down a gas power plant frequently is not economically. But that is why you add a limited battery storage to handly short lived fluctuations and which allows for more planned powerups and power downs.
And lets not forget that lots of grids have access to hydropower which can be used as batteries. E.g. Denmark has excess wind power production, Norway will reduce hydropower production and buy power from Denmark. When Danish windfarms produce less power, then Norwegian hydropower will produce more power and export to Denmark.
Norway exports to several European countries, but is not alone. There is hydropower in Switzerland, Austria and several other countries which can be used more like batteries instead of constant production of power as today.
