As you all hopefully know by now, we are on a journey towards overlayering-free solutions.
One big roadblock on this path was the Inventory dimension concept we have in AX, or, more specifically, providing a way for partners to add new inventory dimensions that would not require overlayering.
Michael has documented the current design we have in mind in a blog post you can read below:
https://blogs.msdn.microsoft.com/mfp/2017/08/10/extensible-inventory-dimensions/
Let me know if you have any questions!