To follow that up: 45W isn't that bad. Depending on where you live, I'd say it's worth it if you get something out of it. (Be able to fit the HDDs, upgradability, ...)
Ultimately you'd need to do the maths. Check what it costs to afford an additional 20W of power in a year and whether you should spend that money on better hardware. If my maths is right, 20W for a year at a high price of 30ct/kWh is about $52. So there isn't that much to be gained. And your electricity might be considerably cheaper anyways.
I think that's a good question. And a nice video. The findings in the paper seem to arrive at that conclusion and we might need to find a better approach. Mind that (as he pointed out) it doesn't rule out growth in AI. It just hints at probable stagnation with the current methods. I'm already fascinated by the current tech and the new possibilities. But AI is really hyped as of now and I too, think we should take the claims of the big AI companies with a grain of salt. I'm sure the scientists at OpenAI are already concerned with exactly this as they do research for the next generations of ChatGPT. It's a bit of a bummer that lots of the research get's done behind closed curtains and we're going to have to wait for a bit longer to find out.