Again, I don't know what the ones that have not yet responded are going to do. However, in some cases, the savings being promised might not come to fruition because the market for payment processing is much more complicated than an interchange fee. Just because you reduce an interchange fee doesn't mean other elements of that overall price are automatically going to fluctuate too. In some cases, some costs might go up.
In a lot of cases, payment processors today compete with one another not just by reducing prices but also by offering value-added services—inventory management and stuff related to fraud detection and prevention—making it a seamless, automated reconciliation. These sorts of things aren't going to be affected by an interchange fee.