It would be logical to assume that Visa/MasterCard are against Bitcoin because is it a competing payment system that would cut into their profits. They are going to fight it, or find a way to adapt and live with it, such as proving bitcoin to Visa/MasterCard gateways.
At least some of the value they offer comes from consumer protection. The charge-backs that vendors hate are beneficial to customers, and since it is customers who have the money there may well still be a market for credit card-like consumer protection in Bitcoin.