ICO will be promising for many more years. It just takes time to regulate what the states of different countries are doing now. When regulation works, then there will be no fraudulent ICO and almost every project will be promising. ICO is the best method for raising funds and developing promising startups! 
I don't think so. Just look at start-ups, more than 95% of them would never succeed. I think ICO procedure is more sophisticated and clear but percentage of successful projects will not be higher than 70-80%.