Right now, in order to switch payment gateways, it looks like we would have to disable the old gateway (at least, within each currency) and force all customers to re-enter their card information using the new gateway.

Building on the payment gateway restrictions that were introduced in 5.11: It would be a much better customer experience - and make the switch much easier - if Blesta could charge stored cards using the old gateway, but switch to using the new gateway whenever a card is updated or newly entered. Then, the old gateway could be disabled after most or all old cards have expired.

I could imagine writing this as a "payment gateway" that's actually a wrapper around two other gateways, but that doesn't seem like a lot of fun.