Of course any tech can be shut down, the biggest risk with rachio versus the B-Hyve that I also own, is the dependency on the cloud. This is why we always have things like GitHub and Raspberry Pi’s to keep us who can use them more independent, of course with some loss of ease of use.
The IoT is a scary new world, look into the possibility of a hacker triggering all Rachio or B-Hyves to trigger all at the same time. Best to keep your use of IoT Devices to a minimum, as a general rule.