I disagree with every point because I think it's all unproven assumption but I will say - yes other things will replace it over time. Other religions. Call them athiestic systems of morality or whatever but it's still the same. But to think there will be a point where most humans won't believe in a higher power seems absurd to me. It's been a natural part of being the only species that recognizes it's own mortality and can communicate. We're only able to speculate about all of this because religion has got us here in the first place