Over the next 100 years or so VR and haptic tech make it so people can become fully emersed in virtual reality. So pretty much everyone does. There are arguments on both sides, but eventually most people choose to live in their own world as a "god" with only VR interaction between one another. Everyone in VR stops having real kids, but thanks to AI improvements they can still have "kids". Technology eventually allows people to plug in permanently while their bodies are maintained by AI and robots systems. Eventually their bodies die, but their consciousness has been captured enough by the system that no one knows or notices when their VR friends bodies die in reality.

In the real world a very small segment of society refuses to join the VR universe and pledge to remain in the real world. Maybe there's some war in there because of this. Eventually though, the population of earth drops to maybe a few hundred thousand mostly wandering communal groups, while everyone else's consciousness is in VR systems. This is good for the planet.

After a few thousand years, the people in reality have multiplied and built a better more equitable world, but have completely forgotten about the people in VR, and the automated buildings containing the computers have become buried and lost to time. Until one day someone stumbles across one of these ruins and begins interacting with the VR people again despite a mythical belief system that such technology is all bad.

Some shit happens and there's a VR vs reality reckoning... Maybe some sort of Romeo and Juliet love story to keep it interesting.