This is as close as we will probably get to a Webcore replacement.
When considering only actions within the SmartThings environment, it seems like the Rules API could do close to the same as webcore with the proper front end. But I would imagine SmartThings isn’t too keen on doing certain things external to itself that webcore does like call external APIs, a custom mobile presence device, subscribe to IP address changes, etc We’ll see once the above tool is released.