In the AX Licensing Guide from february 2016 Microsoft announced a new add-on to retail called; Retail Scale Unit.
Retail Scale Unit
As part of our future offering, we are considering offering a scale unit (Retail Scale Unit) that will enable businesses to run in distributed environment across datacenters to support proximity to physical locations
as well as allow distributed storage and help scale out needs of retail and commerce operations. This offering will allow the ability to add one or more identical scale units that can meet the transactional compute needs of retail and commerce channels. Additional details coming soon.
Even though details have not yet been disclosed on what or how it works, it is now available on sites where you buy Microsoft Licenses. Even prices are available, and it is a service priced per month.
Try to google-search on “E3307B7FD0C149AE9B95E4707C9D1AD7” and you will see distributors that are having this SKU/product in their assortments. Stay tuned as more will be explained as Microsoft makes more information available, but this is great stuff for all retailers!