I would like to propose to allow to an user to be the admin (always under the supervision of the real admin of the forum) of a subforum so that he can organize it like he wants. with this, the owner of the forum could give small responsibility to other user and not to put in danger all the website.
I know that this change suppose many change in the code but it is just an idea for the future.
Give the admin's permissions to an user but just from one subforum to their children.
Give the capacity to create sub-subforum and organice the subforum in the way that he/she wants (using mod such as Blockgets) but alway under-control of the admins's forum