If we assume this is true, then it's a massive problem for AI. Building energy infra is slow and hellishly expensive. Near and medium term use cases just aren't compelling enough to start upgrading the power grid.
I wonder how much of this over supply can be taken up with AI training and how much that would change the calculations.
If we want an alternative I think we'd need to try alternative training algorithms that are easier to distribute. Predictive coding for example can approximate backprop, but requires more compute. Something in that direction might work https://arxiv.org/abs/2006.04182