The technology for addressing baseload exists: renewables, batteries, and long term chemical storage (like hydrogen). All these exist, it's just a matter of pushing the costs down via deployment and experience.

If you object to these because they are not scaled out, I will point out that a nuclear powered world will also need new tech of that kind: either seawater uranium extraction on a massive scale, or a breeder-based fuel cycle. Existing burner reactors would, if they powered the entire world, exhaust available uranium resources in just a few years.