Bag-in-the-box containers can keep wines fresh for four to six weeks after they're opened, thanks to the vacuum-sealed bag inside that collapses as the wine is consumed, making it difficult for oxygen to get in and spoil what's left. Although box wines often come in 3-L sizes, equivalent to four bottles of wine, more convenient 1.5-L boxes are becoming available.
The article concedes that bag-in-box has a certain advantage over the "juice box":
Juice box--style cartons don't offer that extra shelf life once opened, but they are more eco-friendly than bottles.
Thanks Sharon Kapnick and Time Magazine