I worked with some YAGNI zealots and this was a routine experience. I adopted the philosophy of IYHTAYPGNI, "If You Have To Ask, You're Probably Gonna Need It".

Will you really need a migration for that? OP's storage is already in depth-first order, so subtrees are easy to fetch.

Exactly this. You plan around what might be needed in the future. I've found some extra work now is usually a lot less work in the future.