Sadly, I'm with Ken on this one.
Much of it is about availability, convenience, and consistency. Just last week I was in Salt Lake City at a trade show. There was a Starbucks in the lobby of my hotel. So instead of getting in the car and driving halfway across the city to a 3rd wave cafe that
might have better coffee (depending on which barista was on duty), I just popped down to the lobby and got a straight shot and a skim latte. Although I had to choke them down, I knew exactly what to expect and they were much better than the coffee in the Concierge Floor lounge, which had no-doubt been sitting there for hours.
Starbucks made its mark by offering a variety of creative and fun coffee/tea drinks that are a heck of a lot better than the dreck you find in most hotels, restaurants and offices. They perfected cookie-cutter processes to make sure their drinks are the same wherever they're served, and they provided thousands of locations for easy access.
But American consumers don't go to Starbucks for the taste of good coffee. They go for the quick, convenient coffee/milk-flavored sugar and caffeine high/jolt. Like all fast-food chain products, it's consistent, dependable and available everywhere. You can get roughly the same drink at any of thousands of locations around the world. If you drink Grande Hazlenut Lattes in your homeown you can be sure that you can get one at an airport halfway across the globe and it'll taste just about the same.
McDonalds and many others have made fortunes from our national insistance that everything must be predictable, even if it means sacrificing quality for "good enough". That's what makes Starbucks particularly vulnerable to McDonalds and Dunkin' Donuts. Those chains have vast and long experience in catering to America's obsession for consistent mediocrity, and they know how to do it faster and at lower cost. And they have a lot more locations. They also have drive-up windows so you don't even have to get your fat *ss out of the car. The quality may be a smidge below Starbucks, but that'll be OK as long as it's hot and a little cheaper. Starbucks may live and die by the superautomatic.
Yeah, Starbucks will probably retain the upscale crowd that wouldn't be caught dead at a fast-food joint but doesn't understand fine coffee either. They have the advantage of somewhat better quality coffee (though usually stale and always badly roasted), a large variety of drinks, decent baked goods and other munchies, and a comfortable atmosphere for those who want to sit at a table and surf the web.
But I wouldn't buy any Starbucks stock right now.
The 3rd wave may continue to grow in popularity, but it's unlikely to make a dent in the business of any of the chains, even Starbucks.