[I'm the Cloud SQL TL] I can't comment on timelines, but we're aware that customers are interested in more features around maintenance window scheduling, deferral, and notification, as well as shorter downtime for updates and smarter scheduling within a group of replicas.
[I'm the Cloud SQL TL] Confirmed. We know it's a problem that we need to fix. HA reduces downtime in unexpected failure cases (live migration for your primary only helps in planned shutdown cases, not if the physical machine fails), but doesn't currently help with maintenance-related downtime.
