I think it is a system that has a lot of potential to add a new reason for collecting if they make it possible for us to obtain an item that gives us new icons and borders for the tabard, I have some suggestions that I would like to see implemented in the future.
1 - Modify all the customization options so that they are drop-down and we do not have to go through them one by one, that is, being able to do the same as when we change our hairstyle, hair color, face, etc.
2 - Add more colors for the border color and icon color, at this time the color palette that we can use in the border and the icon are very few compared to the background colors, I suggest adding as much as possible all the colors we have for the background in the colors we can select for the border and icon.
3 - Add an option to choose if we want the belt to be hidden in the tabard (old) or for the tabard to have a belt (new).
4 - Add an option to modify the bottom part of the tabard, for example, if we want to hide the front part and keep the back part, hide the back part and keep the front part or completely hide the bottom part of the tabard, similar to how do some belts.
5 - Allow you to customize the design of the upper and lower part of the tabard independently, that is, being able to decide if we want the border of the upper part to be of a specific style or color and the lower part to be of another color or design different, also allowing you to add icons or some new design at the bottom.
6- Improve the textures of all the icons, borders and the background of the tabard so that it is in line with current times.
7 - Add a system that allows us to add new icons or customization to the tabard, similar to what they did with Dragonriding, for example, if you are exalted with Stormwind you can buy an item that gives you the design for the icon and perhaps for the border of that reputation, or if you go to a dungeon or raid you can obtain something like this from a boss, this would allow you to recreate many tabards that have never been added or perhaps create new ones, even serve as an excuse to bring back old tabards but updated, for example, If you are exalted with Argent Dawn you can obtain the icon of that reputation and be able to create an updated Tabard of the Argent Dawn.