I'm not convinced at all that we can turn things around. Most likely scenario is that we will just keep growing, there will be a massive die-off at some point, and then the remaining humans will ensure survival of the species.
Although the UN is predicting continued growth until 2100. It would be pretty amazing if we stopped expanding in 2025.
Nuclear power can easily solve our energy problems as desired. If it comes down to it, and there are no other options, they'll turn back to nuclear power. Most likely the radical acceleration of solar will solve half of our energy problem all by itself.
I see no reason why a die-off would occur due to population growth.
'Peak child' has already been reached so I struggle to understand what you don't think peak population will follow.