As the the question, "what do you think will motivate a consumer to use an irreversible method like Bitcoins to buy something online instead of their Visa card?" the answer is very simple. Lower transaction fees over the Internet, and eventually merchant discounts. Once upon a time, cash was cheaper than using a credit card, until the credit card companies got wise and started demanding vendors sign contracts to not advertise prices lower than the credit card prices. This is why the dual price displays on gas pumps disappeared in the 1980's. But you can still get a cash discount from such vendors on larger items, such as a new tv, if you know who it is in the store you have to talk to.
So you think a possible savings of 1-2% will be enough to make most consumers willing to forego the fraud protections and grievance procedure that come with their credit cards? Won't scammers take advantage of this and set up online Bitcoin shops that advertise lower prices without ever actually delivering anything? I'm no expert in economics, but as a consumer I can tell you that I value the peace of mind that comes with using my credit card for online shopping far more than a tiny potential discount. For Bitcoin to have a chance at becoming a currency, this issue can't be shrugged away: the case will have to be made that one won't lose their money if they buy from what turns out to be an unscrupulous vendor or no one is going to use it.
Online vendors, for the most part, don't sign such agreements; and even if they did, they could be undercut by another website selling the exact same products for bitcoin only.
This sounds like something you completely made up. Do you have any evidence that online vendors aren't under contractual agreement with the credit card companies to not offer discounted prices on other forms of payment?