As the author of ST_Anything, and as an owner of many ThingShields, I can assure you that I will be continuing to support and develop the ST_Anything library. Plus, it is all open-source and available on my Github repository. So you should feel alright from that perspective (i.e. you can always modify the code yourself if necessary! )
As for the hardware itself, my experience is that it has been rock-solid. I have not had any failures of the ThingShield boards.
All that being said, I completely understand where you're coming from. I am already thinking about how I can remove the dependency on the ThingShield, and replace the Zigbee communications with Ethernet. This would allow all of the re-usable ST_Anything library components to work with either the ThingShield, or an Ethernet/WiFi shield. You could probably also run it on a ~$10 Node-MCU ESP8266 with built-in WiFi. Thus, users would have a path off of the ThingShield while maintaining their investment in the Arduino hardware, software, and associated wiring, enclosures, etc...