Pretty smart to leave bitcoins for your children because that will make them rich and they don't have to worry about taxes or anything. But maybe it will be for nothing because bitcoin may always go down and maybe another coin will become important.
Bitcoin has a big future ahead and other cryptocurrencies i think has a long way to go if they want to overcome bitcoin. Yes, it is possible but i don't think it won't happen in the near future. Much better if we earn our bitcoin and save it for the future of our family.
There are chances for such to happen but dont worry that is not coming in this century at least. Bitcoin will be the coin of 21th century and it will remain till a long time ahead. Our children will definitely need this bitcoin as their inheritance because in future everywhere there would be bitcoin coming and going so they will enjoy the life in comfort and happiness ahead.
We can saving Bitcoin for our children, but don't let them depend on that amount. Bitcoin is still a future currency, there's no one guarantees this currency will become the primary currency in future. Therefore, you should saving other assets for your children too. Example gold and real estate, these things are my favorite assets for my child.