I wrote (rather poorly) back in October about fusion and its potential positives. In the middle of December, we had a breakthrough of incredible proportions.
For the first time, it took less energy to start fusion and sustain it, than was released in the reaction. This is obviously essential, as if it takes more energy to get the reaction to take place, than is generated you are using electricity not generating it.
Now, importantly we are not there yet. More energy was released, but there was no attempt to capture the energy. Obviously, once capture starts, you need more energy captured than it took to make the reaction take place as well.
However, should all this work take place successfully, then in a decade (or more like 2) fusion energy could power civilisation. Unlike fission which powers current power plants, as well as nuclear bombs, fusion leaves behind no radioactive waste than needs to be safely stored for thousands of years. Furthermore, there is no chance of thermal runaway. This is because if it goes out of control then it simply goes out.
Due to the delay, this should change our course very little. We still need to move away from fossil fuel burning, electrify travel heating and decarbonize electricity generation, but it suggests that should this be successful, electricity could become so cheap in the future that there is no point in metering it.