Amazon’s significant expansion into yet another market — this time, grocery stores — dominated many of my conversations last week. Clearly, Amazon warned us. I’ve been here before — you see, back in the 1990s, when Amazon was just books, I was running the company’s e-commerce unit. I got into an argument with one of the analysts focused on Amazon, who believed the company wouldn’t go beyond books. I argued that the model it was using could — and would — expand to other things, but even I wasn’t thinking broadly enough.