You are talking about music being feature of merchandising and branding for non-music products and services.
Some of the interactions between music and products will involve advertising or be advertising-related, but you are really talking about a bigger sphere of interactions that just advertising.
So, I don’t think that this is correct (quoting from your post): “‘Advertising’ is the word for this kind of relationship between recordings and products.”
If I were going to pick one word for this, it’d likely be “marketing.” But, I think even “marketing” is a bit over-specific.
I’d suggest the phrase: “merchandising and branding,” e.g., the new music business is about making money off music that plays an integral role in helping businesses define and sell their products.
You could say that some music may become so integral to the future of product merchandising and branding, that musicians’ stake in product sale commissions will be greater than their stake in CD sales.