Let's talk about this directly: what do you do when the nuclear reactor goes down because it's time to refuel, or because it's heating up the river too much in a heat wave (eg in France), or because some sensor valve froze shut in an decade-frequent cold snap (Texas)?
You get the power from some other generator on the grid at a different geographic location.
We can easily get to 80%-90% renewables that way, with current lithium ion storage, and no price decreases. With price decreases, and the huge panopoly of other storage chemistries that are close to shipping, and maybe even competing economically (iron, maybe vanadium flow, maybe zinc air), then we have clear paths to 100%.
But even in France, nuclear never beat this 80%-90% mark, and it would absolutely bonkers insane and unrealistic to consider keeping the US's nuclear percentage at its current 20% of generation, because we can't build and we need to replace ~100 reactors very very very soon. We will be lucky if the nuclear industry could even deliver 10% of electricity needs in the future, because they simply can not build and deliver on their promises. Especially with electrification expanding energy consumed as electricity versus fossil fuels in the coming decades.
Pumped hydro is also very expensive compared to lots of lithium batteries. We will soon be producing many TWh/year of lithium ion, getting to tens of TWh/year by the early 2030s. We can accelerate that curve, or decelerate it based on investments and regulatory structures.
Nuclear is too far behind on tech to catch up. We simply can not grow the workforce or the supply chains of reactors quickly enough to sustain past construction levels at this pace. It would be foolish capital allocation.