Solar, wind, hydro and geothermal are going to be important parts of the mix (perhaps even the dominant parts in many places of the world) but all have unsolved challenges that are much more difficult than nuclear. Storage ofcourse, the world is almost already maxed out on what hydro it can build, geothermal is only viable in very few places in the world. Solar is gated on Chinese polysilicate and cell production unless some other country wants to step up and make what is needed.
Don't make good the enemy of perfect. Nuclear is a very good option to killing off fossil fuels in addition to the obvious renewables.
It also provides key features that they don't, like being almost entirely independent of weather and geography, good in places like Japan that are hard to build other renewables after they max out on hydro. They have no space for solar, wind is hard to build with their terrain, off-shore wind is hard because they have too many tsunamis and adverse conditions etc.
Renewables good, nuclear also pretty good, coal and oil bad.
If nuclear is replacing coal and oil we should be happy, if we are building it -instead- of cheaper renewables despite having the correct sites, enough storage and enough supply then I would be against it but we aren't. The economics of renewables should put them at a consistent cost advantage to nuclear except the cases where they aren't viable - where nuclear should be able to slot in.
Until we have found ways to drastically cut down power usage AND to store huge quantities of energy OR found another similar and cleaner and safer energy source, we will need it in the mix to balance with other renewable sources.
And I am sorry to say but the many countries have made great strides on running their countries on more and more renewable energy sources.
In 2018, Scotland generated 98% their energy from wind alone.
Denmark 72%, Germany 45%, Uruguay 97%, Norway 93%.
It's a whole patchwork of solutions, depending on geography.
Nuclear is not this magic bullet, and just means flipping a switch, it has a major cost, logistical, technological and risk overhead associated with it. If you are France, great, but they have been doing Nuclear since the beginning, it doesn't mean that the world has to do the same, when far simpler, cheaper and safer alternatives are in abundance.
Usual fluctuations (eg. no photovoltaic by night, more wind in the afternoon) can be planned for, but local events such as big clouds or no wind are frequent but have a great impact on
Germany is doing Sektorenkopplung, so attempting to switch everything over to electricity.
This is done because electricity is more efficient and we will use less total energy for the same effect. E.g. a heatpump can make available 3-5 times it's consumption of electricity as heat, where a gas stove can only reach 1.
But many people think this way instead: we have the technology for all the parts => build all the good stuff right now
Ironically, nuclear is selectively framed as just one thing with every safety issue ever, while fossils are further sub-divided into different environmental impacts.
There seems to be a tendency by pro-Nuclear people, to try and frame nuclear as the only alternative energy source. They will say things like, "nuclear is by far the safer option, especially considering coal or gas"..
They keep trying to frame the use of nuclear next to fossil fuels, while pretending that solar, wind, hydro and geothermal haven't increasingly been adopted for 10 years now.
It is a very selective way of framing nuclear.