You are talking about bitcoin transference to your children so there is two things first and most important thing is that there is no surety that how long bitcoin will persist so if your buy bitcoin for the transference of money to your children then no guarantee that at that stage what will be the cost of bitcoin? Will there be any value of bitcoin? people will still believe on bitcoin?

Future is unpredictable and leaving such an expensive thing the value of which is not known and even existence is unknown is something most risky.
The second thing is that is there any individual who you can trust to share your private key with that? If yes then you can but I don't think that in today's age there is such a loyal personality present who will share the message of your money to your children.

I will suggest that buy some property and make some apartment so you can share these assets with your children easily and without any hazards. Every individual has own perception but I think as Compared to bitcoin this idea is better in order to give them profit as well as having less risks.