You raise a very nice point Grant. The world is changing and it could be possible that in the near future the world might not see the needs of cryptocurrency.I think if you want to go that route, be my guest. But I don't feel like crypto is safe enough for savings. I think instead if I were to invest in crypto, I would do so in small bursts, make money and cash out, and rinse and repeat until it's not worth it anymore.
I think getting them a savings account that doesn't go up or down in price is the ideal route to go, because that crypto you have saved for your kids, could be worth next to nothing by the time they get their hands on it. That's the risk with crypto, so I'm not so sure I think it's a good investment for children, at least not in the sense of them controlling it. But I think we'd need to take that money out at certain points, because what if it does fall to a low amount at some point? And what if it doesn't go back up in price? That's like losing a savings all in one shot, and with crypto, there is always that risk.
Saving your money in maybe the US dollars or the Great British pounds is also a nice idea if you are not interested to directly invest in cryptocurrency.