It’s too soon to say whether inventory data will become a “commodity.” However very soon consumers will be able to do online product research and then learn, fairly quickly, where they can buy the desired product offline. This is the future of online shopping and any shopping engine or online shopping portal that doesn’t incorporate this local data will be doing so at its own peril.
I tend to agree with this prediction. Mixing current CSEs for online shops, local information – including maps – from Yahoo! Local for instance, and inventory of offline shops – don’t forget a bit of social shopping – could be a powerful combination for shoppers. But building such a service will be a big challenge for user interaction designers.