Howard Schultz has said he wants Starbucks to be the "third place'. The first two being home and work.
It looks to me ithat is exactly what is happening. Informal and comfortable with friendly staff and with no fast food aura.
If you had to pick a place to meet a real estate agent for a quick meeting or a coffee first meeting with an on line date would you suggest to them Dunkin Doughnuts or McDonalds?
So Starbucks really is unique and hard to see any credible challenger on the horizon.