They'll drag their feet until they can't. It's a go first bunch-up. Eventually someone will do it as a competitive advantage attempt and the rest will fast-follow (you see this happen frequently in such markets, as with the $0 stock trading bunch-up & fast-follow that happened recently).

The various US credit card & processing companies have an extraordinary thing going for themselves. Visa and Mastercard have cartel-like margins (Visa's operating income margin for 4Q19 was 66%, you don't see that outside of maybe illicit drug operations or Facebook's monopoly in its earlier thinner incarnation pre-Russiagate). They're super sensitive to giving any ground on their fee levels, out of fear (correctly so) that they'll never get them back.

Before the market drop, Visa was worth more than all publicly traded banks in Europe combined (frankly that may still be true post market drop, as Visa hasn't declined all that much).

The EU had to legislate to get the fees low enough that microtransactions might possibly be reasonable.

Visa etc are now only allowed to charge a percentage, 0.2-0.3%, but the intermediate (Stripe etc) can still add a flat-rate fee.

Makes you wonder how much those companies really compete.