Pages & Menus section merge proposal mockups

Challenge

The relationship between pages and menus is not immediately obvious for new users. How to sort menus, how to remove menu items when you've deleted a page, these are questions that might cause confusion for users when they are handled in two different sections.

Proposal:

Every theme has a "base menu" that's in lockstep with the pages you have, even themes that don't support multiple menus.

Mockups

The "Base Menu" uses the menus section. If you delete a page from "Pages", the menu item is deleted as well. When you sort a "Base Menu", this is reflected in the "Page Order" page attribute.

The "Page Attributes" panel is revamped to hide the "Page Order" option.

This approach has the following benefits:

The relationship between pages & menus becomes less important, as menus stay in sync.
Menus section isn't moved.
Older themes that don't support menus get the added benefit of being able to easily sort their menus, they just can't have multiple menus.
The "Page Order" legacy feature is hidden behind a UI that's the same whether or not you use menus.