Yes, I'm aware of this problem. First, we're unlikely yo be acqui-hired, because we're based in Russia. Second, I simply don't believe that this app will reach the levels of success similar to Wunderlist or Todoist :)))
But I definitely think that there should be a legal way of protecting existing users of an app from "Our Incredible Journey". Maybe some clause that permits the authors to open-source the app.
Are there any examples of this in the industry?