My former employer did exactly this (dev incubator it was called) with people from the call center. During the time I was there one guy turned out to be a geni

My former employer did exactly this (dev incubator it was called) with people from the call center. During the time I was there one guy turned out to be a genius and after a few years left to work for a big bank and another guy got enough experience to start his career as a dev somewhere else. The rest of us learnt a lot mentoring these guys and feel quite proud of them. This was no more than 5 years ago.