We don't know which rates Visa/MC are actually raising yet, but probably not. It has a lot to do with how/what processors charge.
Along with lowering costs, Optblue let processors add a markup to Amex transactions. (Previously they couldn't. That meant no incentive for processors to suggest or push Amex acceptance, as they didn't make money on Amex transactions.)
Now they can, and those markups tend to be higher than for Visa/MC. In egregious cases, the processor simply continues charging the business the old Amex rate (~3.5%) and pockets the entire difference between 3.5% and the new lower rates.
Along with lowering costs, Optblue let processors add a markup to Amex transactions. (Previously they couldn't. That meant no incentive for processors to suggest or push Amex acceptance, as they didn't make money on Amex transactions.)
Now they can, and those markups tend to be higher than for Visa/MC. In egregious cases, the processor simply continues charging the business the old Amex rate (~3.5%) and pockets the entire difference between 3.5% and the new lower rates.