Given the limitations of classic navboxes, and the similarities between categories and navboxes, it makes sense to create dynamic navboxes using a semantic structure.

I propose a visual block associated with a given Category page.

Limitation 1: Navboxes are typically manually organized, but often have an underlying sort order that is alternative to alphabetic order.
Solution 1: These boxes should be have links dynamically added whenever possible. One or more alternative sort keys should be available to be placed into articles using a new magic word.
Limitation 2: Navboxes work well when there is an atypical category intersection. Few well developed category intersection extensions can fill this role.
Solution 2: A parameter placed in the Category page can indicate where a specific Category intersection should produce a visual row / group.
Limitation 3: Classic navboxes still frequently will appear on articles in an expected way.
Solution 3: These boxes should be embeddable in a page via a new magic word to indicate the category hosting the original dynamic box.
Limitation 4: Some rows in classic navboxes are derived from "subcategories" and not intersections.
Solution 4: While not commonly used, "/" slashes are valid page names. These can automatically indicate a row to be included in the parent category's navbox.
Limitation 5: Many of the issues with SEO and UX of classic navboxes are due to how arrays of links are displayed in an unfriendly format on mobile platforms.
Solution 5: Display links in another format, such as Material Design chips.

These solutions can create elements to overcome many of the interface challenges that currently impede classic navboxes that have not fundamentally changed in 15 years.