Storing wind/solar energy for a long enough duration to prevent long-tail blackouts, while also transitioning buildings to electric heat, is a pretty big technical problem.
Pumped hydroelectric storage is a "big" problem in that the scale is large, but it's not particularly complicated. The solutions exist, and they're comfortably boring, and trivially scalable and redundant.
Moreover, we're still pretty far from the point where this even becomes an issue. We can accelerate the deployment of renewables a lot before this is a real constraint on anything.
We don't though, or we'd be using them. Nuclear is clearly the only current technology that can provide the same type of grid available electricity that we're used to AND actually exists Now.
That is twentieth century thinking. Central power plants with a grid to distribute
In the future (I predict) it will more and more be distributed both production and consumption.
The technology all exists. But it does not suit the concentration of power. It will take democracy (people taking action - perhaps direct action) to avert the catastrophe.
Problem is it will cost the rich and powerful a little opportunity cost and a bit of wealth.
The looming climate catastrophe has political and social solutions. Not technical ones.