Walt Mossberg in his final weekly column:

Microsoft is still trying to find a way to meld its formidable software and cloud expertise with a significant hardware business. The ad-based business models of Facebook and Google, now so dominant, could prove fickle. And Amazon has only had one really giant hardware hit — the Kindle — in its existence.

The entire article is excellent and worth a read. But this passage is fantastic, the setup leading to that last line about Amazon is perfect. I had never thought about the Kindle in that context, but once I read that — it is so clearly true that it amazed me a bit in the realization.