To build robust systems, you ideally want heterogenous, redundant architecture, which translates to the same set of systems built on different platforms. Statis

To build robust systems, you ideally want heterogenous, redundant architecture, which translates to the same set of systems built on different platforms. Statistically speaking, unless there is something incestuous going on you aren't aware of with your cloud providers, it is unlikely all of your providers will go down at once. Reconcilation and graceful fail over/propagation of state is left as an exercise to the student.