But that's excactly not was it happening. Keeping the remaining reactors alive (they provided ~2,6% of the generated electricity btw...) just for the sake of keeping them would have slowed down renewables (as those old reactors are definitely not fit to adapt to fluctuations well) and would also have bound a lot of money then missing for renewables and infra-structure (why upgrade the grid to better renewable fluctuations when the reactors can't anyway).

So they actually start right now and massively so to build up renewables and the matching infra-structure. Unlike countries with alleged nuclear plans, that all still plan to start building soon™ and in most cases not even close to the actual required numbers for the projected demand in two decades+. Because completely decarbonising transport, industry and heating means a massive increase in electricity demand as we basically shift all primary energy demand over to electricity. Yes, in some cases electrity will be more efficient and will save some energy. But we are still talking about all primary energy, with electricity today often only making up 20-25% of the primary energy demand in most countries today.

PS: But yes, if you want to build nuclear. Start today. But do it on a scale that you will be actually able to cover the minimal required base load of your projected electricity demand in 2050+... Fun fact: No country actually does. They all just pretend and actually sit the problem out for someone else by loudly planning nuclear but not in amounts that make sense mathematically. France is basically the only country with a somewhat reasonable plan. When they scrap the "8 optional reactors" bullshit and build the bull set of 14. That's their required baseload. And they will need to keep their aging fleet functional until the majority of them are build. They will also not be trivial.