For your application though a failure is a failure in any scenario. EBS went down in one zone and was slow in a couple others for a few hours, it's a bad downtime but some services survived the problem relatively unscathed. This suggests that something could have been done to avoid any trouble at all.

If the datacenter you are in has a slight conditioning problem this summer and 10% of your drives breaks down due to excessive heat, how quickly will you be able to re-provision the data center?

About a week after AWS outage the italian ISP Aruba had a UPS failure due to a fire in the UPS room and the entire datacenter switched off automatically during the night. For the following 8 hours that datacenter was off for every customer. How would your new solution handle such a situation?

Designing a hot standby replication solution for MySQL/PostgreSQL that works across regions seems easier to me rather than implementing a database from scratch that should solve a very complex problem.