For actual estimates of how far off human-level AI is, check out page 10 of http://intelligence.org/2014/04/30/new-paper-the-errors-insi... which has a scatter plot of predicted completion dates vs. when the predictions were made. "There is a strong tendency to predict the development of AI within 15– 25 years from when the prediction is made (over a third of all predictions are in this timeframe".