One thing I noticed locally regarding this logic is that the main site navigation is tied to these pages IDs. That is, for example, the 'About' page tab is tied to `#page-about`. Currently that's fine - there can only ever be one page with an 'about' slug. However, with this new functionality, you could have multiple pages with the same slug, under different parents. It may not be an issue, but it's something to be aware of.