To prevent losing your bitcoins you make sure to transfer them to a new address every 100 years (I am not aware of any other method of "proving" you still have access to an address).
The only way to lose your BTC should remain as if you lose your keys or your seed phrase, not if you do not move it for a certain number of years, a censorship resistant and permissionless network cannot work with that kind of restriction or rule. There's no way to know if BTC's in an address is lost, so we should leave it at that, if people lose their keys the funds should remain lost, but if they are holding it for the long term, let them move it anytime they want.