The companies that just keep the bilges dry and the engine running are the ones that we love, but they’re gone because they got made irrelevant. Or they got absorbed into something larger. Microsoft has a bunch of failed initiatives (Windows Phone, Zune) plus a bunch of successful ones (Azure, Xbox, Office 365).
If you’re up for classic books like Brooks check out The Innovator's Dilemma. You have to try to expand in a hundred different directions because you don’t know which one of those hundred directions will be relevant next decade, and you have to be unafraid of cannibalizing your core business because if you don’t eat yourself then someone else will eat you instead.