[abritishguy]

It's a very good question. The stand-in system itself has been built to have basically no external dependencies itself.

So, the question you are really asking is "to what extent are the other parties involved in the processing of payments resilient to AWS failure" – e.g. Stripe probably isn't and that's probably a decent chunk of e-commerce.

I definitely don't think this would be anything close to smooth sailing if AWS was to fully go down, but we do have the benefit that underlying payment infra is still dominated by on-prem with leased lines etc. My best guess of the actual behaviour would be that bank transfers would keep working, the card networks themselves would keep working but the average e-commerce website would not.

Naturally, we can only control for what we can control for – and for us the primary benefit of stand-in is what it gives us in the much more likely scenario of an incident in our platform.