Banana trees* are cloned, rather than seeded. The old banana that artificial banana flavouring is based on, the Gros Michel, cannot grow in most of the world due to fungus in the soil. The modern Cavendish banana is potentially susceptible to the same problem, if some bacteria or fungus shows up that can infect it, there goes our bananas

*Banana plants technically aren't trees, but argue with a botanist about it, trees are stupid