That would be an asynchronous task.
Watching for property changes doesn't necessarily replace events. There are still events in the API, but watching for property changes let's you get real specific on what it is you care about that might change on an object.
It sounds like you want to be able to cancel something like a QueryTask, or the applyEdits or similar. In that case, we don't really have a mechanism in place to cancel a task. It's something we can look at, but once the request is in flight, we could only at best ignore the result, it doesn't mean the request didn't go through to the service and your edits didn't apply though. Once the request is at the server, not much we can do to cancel that.