I do agree that under Bitcoin birth rates will probably rise. I just don't think birth rates are something to worry about. We can't just keep expanding the population forever, at some point it will have to contract and we'll just have to learn to deal with the consequences. But there could also be some benefits. It would shift power back towards the average person, as their labor will be more scarce and valuable. Technology would be utilized to fill in the gaps, freeing people up from doing those mundane jobs. If there are fewer young people they will likely be much better educated. It would be a mixed bag.