I agree that people won't accept degrowth.

This being said, I think that the alternatives are wishful thinking. Better efficiency is often counterproductive, as reducing the energy cost of something by, say, half, can lead to its use being more than doubled. It only helps to increase the efficiency of things for which there is no latent demand, basically.

And renewables and nuclear are certainly nicer than coal, but every energy source can lead to massive problems if it is overexploited. For instance, unfettered production of fusion energy would eventually create enough waste heat to cause climate change directly. Overexploitation of renewables such as solar would also cause climate change by redirecting the energy that heats the planet. These may seem like ridiculous concerns, but you have to look at the pattern here. There is no upper bound whatsoever to the energy we would consume if it was free. If energy is cheap enough, we will overexploit, and ludicrous things will happen as a result.

Again, I actually agree with you that advocating for degrowth is hopeless. But I don't think alternative ways forward such as what you propose will actually work.