Has anyone noticed how many former market leaders are facing major revenue challenges? Sharp. Dell. Best Buy. HP. Penny’s. Pfizer. The list goes on and on. Reading the news, I couldn’t help but notice the Wall Street Journal article “Yellow Pages Last Lifeline: Clinging to Each Other” and draw a connection to so many company plights. Yellow Pages – remember them? The Digital Age has made books of phone numbers nearly obsolete. Just as Blockbuster could have become Netflix with a better understanding of what business it was in, could the Yellow Page creators have become Google (or at least Yelp) with an understanding that the Digital Age would replace searching physical pages with surfing the web via computers and now smart phones? “What business are we in?” is the most fundamental question that business leaders should we asking today. Here are five…