There is no set rule that says you need to get x% of your power from a stable "base load" producer. In many regions of the US you could cover daily demand using a dynamic combination of wind, solar, hydro, and natural gas. The base load power story has been pushed by coal/nuclear advocates to try to maintain skepticism about renewables.

In reality, power sources that have little to no flexibility in power output (coal and nuclear) are not ideal either. They either produce at near capacity or they are offline. You can't throttle a nuclear plant from 80% capacity to 50% capacity. As a grid manager, this doesn't always make things easier.

Plus, the fact that the grid survives when a nuclear plant or coal plant goes offline for maintenance shows that there is flexibility available.

We just need to stop looking at "base load power" as only an advantage and acknowledge that only being able to produce 0 watts or 1 gigawatt of power output is also very inflexible and not always an advantage...