Nuclear could have powered the world easily and we could have done it with 1960s technology. And we could easily do electricity and heating with nuclear quite easily. The only thing that's actually tricky is synfuels and solar/battery doesn't solve that. High temperature reactors using heat to create hydrogen is arguable the better path to synfuels then electrolysis.
And we can go to 100% of electricity from nuclear, we don't have to have this dumb argument about 'the last 5-10%'. Because its reliable.
And if you actually do the math nuclear would have been cheaper then all this nonsense we have been doing for 30 years with wind, solar and batteries. The cost of the gird updates is like building a whole new infrastructure. With nuclear, the centralized more local networks are perfectly reasonable.
I did some scenarios starting in Year 2000 or Germany to all nuclear, vs wind (off-shore, on-shore), and solar (partly local partly brought in) and batteries. The numbers aren't even close, nuclear would have been the much better deal. Even if you are very conservative and don't account for major learning effect that countries like France had when building nuclear.
That said, even with nuclear, having a few Lithium batteries that can go all out for 1-2h is actually a good deal. Its really only about peak shaving the absolute daily peaks. What you don't want is having to build batteries that can handle days or weeks.