Nuclear plants take a long time to build, but decarbonization also takes a long time. The world will not be fully decarbonized by the 2030s. We're going too slowly. That means that reactors coming online in the 2030s can still contribute to decarbonization. I wish that we were decarbonizing so fast that reactors built in the 2030s wouldn't matter, but we aren't.

You can see from my posting history that I am more bullish on renewables than nuclear but I'll take low carbon power of any kind until we've phased out all fossil fueled plants.