Right now, it looks like population growth in the next 100 years will have a huge impact on environmental problems. Unless we find new technologies, population growth will cause there to be much more in the way of greenhouse gas emissions and that is not a good thing. In addition, a growing population will put a lot of strain on water supplies, especially in places like California.
I do not think people 100 years ago worried about things like this. After all, the population of the country was much lower, there were no mass produced cars yet, and there was still much more in the way of wide open spaces where no one lived.
Population growth will have a significant effect on society over the next 100 years. Our population is multiplying at a rapid rate. We are using up the fossil fuels we have available as well as other planetary resources. Looking back over that last two-hundred years is a strong indication of the need for drastic measures to occur before a hundred years passes.
Alternative fuel resources need to be developed, the environment needs to be cleaned up, and humans need to reduce waste. Additional population will mean additional waste on our planet, increased fluro-carbons in the atmosphere, reduced food and water supply, and reduced living space.
In terms of something like the education systems, schools will have to be built and manned to accommodate the increase in population. Available housing will have to increase as well as transportation methods will need to be addressed because highway over load in some areas is already a common problem. There may well be many changes by then that someone my age can only imagine.