There's a limit to how far you can expand hydro. There aren't that many more places to build dams. You can expand a little more by putting reservoirs at higher elevations specifically for storage, but that's expensive.

Even at 4 hours of storage, the scale we need is a bit mind-boggling.

Your link is really interesting though. That's the kind of analysis we need. I see too many articles that just talk about rated capacity with no consideration of actual output or reliability.

My second link does similar analysis for Australia, and there it doesn't work out so well. The wind drops low over wide areas for days at a time.

In any case I have nothing against renewables, as long as they don't use up too much land...offshore wind is perfect. But I think we should be building GenIII and better nuclear reactors, too.