There's no proven nuclear technology that scales to power the world either. Do you accept that as an argument that nuclear should be disregarded?

It's entirely reasonable to assume that some storage technologies will survive being rolled out to the scale needed to allow renewables to reach 100% penetration. After all, there are thousands of different battery chemistries, and many other non-battery storage technologies, including ones using 19th century levels of science (pumped thermal storage, for example). Your negativity requires that all fail. I think you doth whine too much.