Citing sustainability, Starbucks wants to overhaul its iconic cup. Will customers go along?

For a generation and more, it has been a cornerstone of consumer society, first in the United States and then globally -- the throwaway cup with the emerald logo depicting a longhaired siren with locks like ocean waves.

Bethany Patton steps up to the counter and places her pink mug into a shoebox-sized dishwasher. It spins. It whirs. Water splashes inside. After 90 seconds, the door opens and steam emerges. A barista grabs the mug, dries it and prepares Patton's order -- a 16-ounce Starbucks double espresso on ice.

For bringing her own cup, Patton gets $1 off her drink.

"Saving the environment is important and all, but I probably come here more in knowing that I'm going to get a dollar off," says Patton, 27, a cancer researcher at Arizona State University. Two friends who came on the afternoon coffee run nod as they hold the cups that they, too, brought along.

Just as noteworthy as what they're carrying is what they are not: the disposable Starbucks cup, an icon in a world where the word is overused.

For a generation and more, it has been a cornerstone of consumer society, first in the United States and then globally -- the throwaway cup with the emerald logo depicting a longhaired siren with locks like ocean waves. Ubiquitous to the point of being an accessory, it has carried a message: I am drinking the world's most recognizable coffee brand.

Now, in an era where concern for sustainability can be good business, the Starbucks disposable cup may be on its way to extinction thanks to an unlikely force: Starbucks itself.

 By 2030, Starbucks wants to move away completely from disposable cups, which represent big portions of the company's overall waste and greenhouse gas emissions.