At my company they have this legacy system that's been around for a good 10 years now. The company told me they plan to break away from the legacy system, and this was 2 years ago. The reason that nothing has changed is because anyone that knows the legacy system have already left, and there's one service that relies on it. That team absolutely refuses to break away from it so everyone is stuck where they are. Given the attitude of the company employees, I'm pretty sure this legacy system will be around for another 10 years.