In the future that I saw, Humanity has completed its mass migration out into space. A fleet of specialized robots descended onto Planet Earth. Shaped like spiders, they excavated landfills and sent the rubbish for proper disposal. They demolished concrete cities and restored the original vegetation.
Landing near the defunct nuclear power plants and nuclear waste storage facilities, robotic spaceships loaded barrels of radioactive waste into their cargo holds. These barrels will be sent on a one-way trip into the sun. It was simply too risky to leave these toxic waste on the planet.
In the ocean, fleets of white robotic craft began work. The slender ships in front dredged the oceans for large debris and waste materials. The round ships behind purified the ocean waters of microscopic waste.
The work extended into space, where massive arrays of satellites diverted solar energy both to prevent reduce the effects of global warming and to the promote growth of plants in badly damaged areas.
After many years of restoration work finally made the planet fully habitable again, the World Government then declared Planet Earth a Natural Reserve where the use of advanced technology is banned; only emergency medical, transportation, communications and monitoring equipment can be used.
The peoples who desired to live without technology returned and restarted the tribes and cultures of their ancestors. Tibetans, dressed in their traditional robes, inhabited a bustling Potala Palace. American Indians hunted deer on their ancestral lands. The Great Wall of China stood silently, watching over the nomadic tribes.
One day, a half-naked dark-skinned teenage boy walked into a village filled with many stone walls. Newly initiated to adult status, he was draped with white war paint in a zig-zag pattern and many red dots. He came upon the scared altar where he cast a stone onto the wall and sang the prayer of the Star People. Within minutes, a small, white spaceship appeared, taking him to visit the people who lived among the Stars.
An altar allowing space communications stood in the center of every town and village. When children come of age, their guardians bring them to this alter to decide whether they wish to remain on Earth or to go to Space. Every adult has the opportunity to visit or live in any community on Earth or in Space. A fleet of automated, self-maintaining space shuttles ferried visitors and migrants on demand between Earth and all space cities within the Solar System at no cost.