ebook and ecommerce

If e-books become the order of the day, would Amazon or any aggregator will be able to charge a high sales commission (right now 30%) ? In that scenario, the aggregator would be delivering search service for which commission would be very low. Hence ecommerce would move to
a) Diversifying to other goods where physical delivery is required. There supply chain efficiencies, good customer service will justify the presence of aggregator.
b) New tie-in business model like Amazon and Apple are doing. Sell hardware to which you can tie-in your e-book sales.
I think the spectre of future where Amazon and apple would lose its functionality as aggregator of music is playing a big role in forcing these companies in adopting model (b) and not trying to act just as a platform.

The same logic applies for music(mp3). Movies are a different story. There one can have a third business model of being a platform through which movies are sold by content creator (Hulu.com, Netflix).