There's no such thing as "cloud downtime" - it's still servers, data centers, networks, same as everything else.
You need to decide how much uptime you're willing to pay for, how much your service can degrade for how long, and methodically address each level of the hierarchy between you and your customers – and it might be the case that you decide that the ongoing costs of your engineering support for e.g. wide geographic separation just aren't sustainable at the level your customers are willing to pay, particularly if you have something like a CDN helping keep your site partially responsive during less than catastrophic failures.
You need to decide how much uptime you're willing to pay for, how much your service can degrade for how long, and methodically address each level of the hierarchy between you and your customers – and it might be the case that you decide that the ongoing costs of your engineering support for e.g. wide geographic separation just aren't sustainable at the level your customers are willing to pay, particularly if you have something like a CDN helping keep your site partially responsive during less than catastrophic failures.