We've lost the banana before. In beginning of the 19th century, an outbreak of Panama disease swept through plantations growing the Gros Michel banana cultivar. By the 1960s, the Gros Michel was all but wiped out as a viable export crop. Luckily, banana scientists (what a job!) had another strain waiting in the wings, and the world quickly shifted to the Cavendish, the variety we eat today.
But the Cavendish is similarly susceptible to disease. Banana plants reproduce by cloning, so subsequent generations don't develop genetic diversity and an accompanying resistance to disease. In these days of increased global trade and travel, the Cavendish might be more vulnerable to an outbreak. Oddly enough, the culprit could be the same — Panama disease. A new strain of the soil disease has been found on banana plantations, and it's expected to reach South America in the next five to 10 years.