Maybe this is a great opportunity for other stores to challenge the near-monopoly of eBay and Amazon. Create good opportunities for people who have difficulty using bank accounts that accept international transfers and international credit cards. There are billions of people who can not use these services, but who could easily buy Bitcoins and use them for international transactions.
These market places thrive on centralized payment options that are reversible, which Bitcoin isn't. People using eBay absolutely love the buyers protection they offer, and I can't see them switch any time soon.
As far as I know, eBay has always had a bias to rule in favor of the buyer, which adds to people's confidence because they know that whatever happens, they at all times can get their money back.
Based on that I don't see how Bitcoin or any other crypto currency will be able to convince people to use it over the centralized payment options eBay allows you to utilize. Fiat is king and will stay that regardless of how high Bitcoin's price is.