Wicker furniture can thrive for years, but it requires attention. Once a wicker object has dried out completely, it will probably fall apart. But if just a small portion of the object is brittle and dry, it's likely that it can be repaired.
Sunlight is the primary enemy of wicker. Always cover wicker furniture if you intend to leave it outside for more than two or three weeks.
To prevent wicker from drying, moisten it occasionally with a damp cloth or sponge. A good coat of paint will also keep wicker from losing moisture.
Mildew is a frequent problem with wicker, but it can usually be eliminated by cleaning with soap and water -- try Murphy Oil Soap and a soft-bristle brush or a sponge. Wicker can also be hosed down after soaping.
Pets (especially cats, who love to sharpen their claws on wicker) and accidental kicks can cause chair legs to unravel. Train pets, guests, and children to take care, or place wicker furniture in a protected spot. Good wicker, though, will take a lot of everyday wear.