It's incredibly hard to tell if something will work or not. So hard in fact, that you are better off assuming it won't. Because that removes the expectation it has to do well, which is what's really holding you back, not fear. You believe launching will be a success only if it yields a specific type of outcome.

If you call it an experiment, it will allow you to not take yourself seriously, or to turn the project into something else, and even to ditch it if you realize you find something else more interesting. Don't let premature commitment limit your options. Just play.

Brian Eno might have said it best:

  Artists who don't censor their own work: Picasso, Miles
  Davis, Prince. They're all people who just put it out,
  and have almost no critical self-censorship. They say,
  "Let the market decide; let the world decide." You might
  not be the best person to judge it.

  That's a kind of humility, actually: it's a mixture of
  arrogance, which says, "I know I'm fucking good." But a
  humility, which says, "I'm not the person to decide."