It is easy to gauge your chances - ask your target customer. The process is simple: Define who would use your app and why. The "why" is the hard part. If you can build something of value to a group of users, success happens. If you find something that is causing them pain and build an app that alleviates that pain, success happens. If you start with the "why" the rest flows. If you start with the "app" and your isolated thoughts about why YOU think it will be successful, it usually doesn't end that way. Start with the "why" then answer the "how".