We don't have anything that can handle more than an hour or two at the big Gigawatt solar/wind generators and you know it, none of them can economically provide even power at night let alone during peak demand periods. All they can do is help smooth out fluctuations for temporary cloud cover/no wind conditions and such. Technology will have to have a 10x leap or we'll have to wait 30 years for incremental improvements in battery tech to get there. Nuclear is available now. With a "to the moon or bust" attitude that we had in the 60s we could be there in less than 10 years.
Before you build a thing, it has not been built yet. To have that thing, you have to build it first. Having built it, you then have it.
No breakthroughs of any kind are needed for grid-scale storage. It is just civil engineering. It won't be batteries.
Nukes have never, at any time or place, anywhere in the world, operated without massive public subsidy. There is no reason to expect that ever to change.
