Any serious energy scholar or expert would say that storage technology is the key bottleneck. It requires a lot of additional R&D but it is certainly attainable within the next couple of decades.
That's a pretty big assumption. Just because technology has advanced a lot in the last century does not mean it will continue to do so. The technology does not exist. We don't even know if it's technically possible to ramp up storage that much. And if it is, we don't know what resources it will depend upon and in what quantities. It may be infeasible or even impossible given the resources on Earth. And even if it's possible and feasible, we definitely don't know how long it will take us to figure it out. Could be a breakthrough tomorrow, or a long hard slog that takes 100 years. No way to know.