I don't think they would ever disappear completely. In highly trusted environments, just a tad of convenience is enough to justify using them.

The most basic custodianship model is the debtor. I lend you a 100 bucks because I trust you, and you will pay them back to me one of these days. You are kind of acting as a custodian.

Now create a social cluster with a lot of trust and probably some person might arise as the central hub that tends to manage debts and accounts. Perhaps it could be the most popular merchant in the local bazaar.

This naturally lends to creating custodianship relations. And I guess that, in trusted social circles where the risk of rug pulls is negligible, it's just fine. Even if they could settle easily. I mean, I don't need to settle with grandma every time we have a financial interaction.