Baseload + peakers is one concept that allows a grid to meet demand. But it's not the only way - decorrelated intermittent generation + peakers could work too. But what doesn't work well so well is baseload + intermittent generation. If you must have baseload (i.e. nuclear) as the foundation of the grid, intermittent renewables (solar/wind) aren't going to have much of a place because you need dispatchable power generation to fill in the demand peaks.

As long as we need peakers or other dispatchable powers supply, I like solar and wind over nuclear to provide the main quantity of generation vs nuclear. I don't see nuclear catching up to renewables on cost terms at this point.