From "Crossing the Chasm" to "Digital Transformation"- always worth reading Geoffrey Moore.
Read his article but the options are not necessarily as brutal. Your legacy infrastructure need not be thrown away. Major insurance companies have gratefully found this out with 360Globalnet.
Won't be an option every time but if you don't want to "throw away the baby with the bathwater" start there.
And he's right about this- no time for three year plans. It is, to quote him, a ROE decision!
Return on Existence
Your enterprise’s business model is already under attack from digital disrupters. They have spotted the inefficiencies in a marketplace whose processes and infrastructure were deployed in a prior era. They have seen how with digital infrastructure they can do your business in ways better than you can. And they are attacking your customer base right now.