I'd be curious to know what other markets have diminished because of smartphones

* Flashlights? Sure a smart phone is not a good flash light but it's often enough

* paper notebooks? I'm just guessing the majority of people keep notes on their phone, probably cloud backed so they can access them on their tablets/notebooks/phones

* video cameras? The article was about compact cameras but I have to imagine no one buys a video camera anymore

* mp3 players

* calculators

what else?