If we decide to do massive geo-engineering, it's not going to take 100,000 years to accomplish whatever goal we set. With nothing but pure hubirs to back me up, I'd say it will take 500 years, but more like 100.
We're very smart over a long enough time scale and we will likely live in harmony with the Earth, at least asymptotically so. It'll never be perfect, but it will get close.
How are we going to achieve what is necessary to turn things around when governments and people are asleep at the wheel and just continue business as usual.
Are people willing to change their destructive habits, i.e. willing to drastically reduce their meat & dairy intake?
Are organisations willing to become more sustainable rapidly and not just do drip feed changes over the next 30+ years.
Or just things that have improved human life without looking at the environmental destruction that occurred over the past few decades.