I'm not so sure that estimate makes sense. It's kind of hand wavy. The sun's output will increase 1 percent every 100 million years. So even at 108% of what it

I'm not so sure that estimate makes sense. It's kind of hand wavy. The sun's output will increase 1 percent every 100 million years. So even at 108% of what it is today in 800m years that doesn't seem like it's enough to lock all the CO2 in the rocks. But let's say for the sake of argument that CO2 does start being sequestered.... well it's a greenhouse gas so as it is removed from the atmosphere... the atmosphere should actually cool down. Plus Earth has self cooling mechanisms that work against an increase in solar radiation. For example Volcanic eruptions and your basic water cycle. More energy would create more moisture in the atmosphere and in turn more cloud cover blocking out the sun. If the amount of CO2 in the atmosphere was way less even at 108% of the sun's output the atmosphere could remain cold so I think a new equilibrium will develop and be sustained for quite some time.