I dunno, i feel like if i had a kid I'd make them go through a tough challenge to find the keys to the coins, provided they are worth anything by then. Nothing in life is free.
You are right, nothing is free. It is fun to play with the thought that in 20 years, there will be headlines about time locked assets as inheritance from the first crypto-parents.
Unfortunately i think the headline will be more like "Funds locked away for decades unlocked in shocking new exploit of system time clocks" or something stupid like that.
True, that can also happen. There is physical services that can give access to a bank box or similar on certain dates or event, but these are less and less available (and expensive).