Setting up e-commerce arm for traditional importers, wholesalers, and trading companies? Thoughts?

Ordering from Alibaba and selling through Amazon, Etsy, etc has become all the rage for new entrepreneurs trying to succeed in e-commerce. However has anyone here worked with established, traditional importers and wholesalers to set up an e-commerce retail arm for their business?

It seems like an interesting business that cuts out a lot of the risk and issues to do with product sourcing. You convince them to work with you to set up a retail site and amazon account for their existing business and you control the online marketing. Then take a % cut of the revenue you bring in. They simply have to ship the product from their warehouse (which they already have and use).

Same business, but you provide a service (less initial investment) instead of the product. Thoughts?