I'm not aware of all online wallet's policies but my guess is that some of them will open their users accounts after some years of inactivity anb get their coins.
if you hand over funds to an online service. the funds are no longer your "property".. but instead "credit" held on an sql database
imagine it this way
imagine you had FIAT in your checking account. but you decided to let someone 'manage' it for you. first deposit into their account
then later
you do not personally reach into their pocket and sign the checks for them to just to post. instead you tell them (withdrawal request) how much you want to move and where you want it moved.
they then check their little book to make sure you have credit(sql database). and then they sign the check with their handwriting moving funds from their holdings to the destination..
if they cannot identify you as the credit holder(forgot password). you will not be able to request funds moved. and you definitely cant sign a transaction because the funds are on only recognised by signatures made by the other person. not you
in short
do not rely on online services. dont rely on passwords.. unless you have the private keys, you have nothing